Thursday, November 30, 2017

time series - Transaction Data with Participant ID


For my master thesis, I need high-frequency data with the market participant ID or which identifies the trading parties, respectively. I don't need the entire orderbook but just the matched orders with a trade direction. I've found LOBSTER so far, which has no MPID though, and tradingphysics, whose Times&Sales dataset would be perfect, if the MPID wouldn't be missing for most of the trades. In existig papers researches either use a special dataset which identifies HFT traders directly or use proxies to identify them. If you could give me a hint where to get such kind of data, that would be great.



Answer



Market participant ID data is extremely unlikely to be available without the collaboration of regulators and the exchange itself, as it is a closely guarded information. Even "anonymized" data with no reference to a specific firm could reveal private information to informed market participants. If obtained at all, it is likely to come with draconian restrictions on access, granularity and publication of results. For example, I know of an official sector researcher who had to keep his entire research project secret for over a year before the legal and regulatory hurdles were cleared even though he already had the data in his possession. Good datasets for any period of time greater than a day are also likely to be costly.


My advice to you is to contact someone who did research with similar data and find out if there would be a way to find access it in one way or another. Talk to professors in your institution, they may very well be in contact with someone who fits the profile.



Best/Standard Practices for Creating & Building Help Files for End User


Anybody know of any best or standard practices for creating help files/guide for software for the help of the end user?


This is a software that has many features and options where the user would need to see how to utilize these features and access them to implement.


Any help or direction with this would be appreciated.




interaction design - Radio buttons or Toggle switch for one out of two options?


I am a bit confused on what should be used when you have to select one option out of the two possible options. Working on a touch screen interface


For ex 1- Selecting a Tax type in a retail store, Options are Inclusive and Exclusive enter image description here


enter image description here


Ex 2- Selecting a discount type


enter image description here



enter image description here


I can't figure out how one option can be preferred over the other in cases like these. So, can anyone tell me a reason or two to choose one over another in similar cases like mentioned in examples.



Answer



I think you're referring to toggle switches here. That being said, Radio buttons let users select one option from two or more choices whereas a toggle switch mimics a physical switch that allows users to turn things on or off.


You can also refer to these UX guidelines by Microsoft on when to use which control:


Guidelines for toggle switch control


Guidelines for radio-button control


Edit: As we're dealing with just two options, you can use radio button for touch interface provided they are easy to tap.


From the screenshots, it seems you're working on a non-touch UI (taking a hint from dropdown). This and that we're dealing with just two options here, I would recommend radio-buttons for this use case. Had it been more than three options, I would have gone ahead with a Toggle Button (not a switch)


Wednesday, November 29, 2017

How to avoid 12:00 AM midnight/noon confusion in a time input field?


I recently specified the wrong deadline for an assignment, for a "dropbox" in the D2L course management application. I was trying to choose 12:00 noon, and the time entry field showed 12:00 right below 11:00 AM, as shown here:


confusing 12:00 AM dropdown menu


But of course, what I had done was specify 12:00 AM, which is actually midnight, a famously confusing time specification. (In my case it was also a time which had actually already passed, and the application actually created a deadline in the past.)


It seems to me that this is an especially confusing input form, since the 12 is below the 11, clearly suggesting that it comes afterwards in time.



In this case should the 12 should show up at the top of the menu, above the "1"? Or should it be at the top listing "midnight" if the AM/PM indicator is an "AM", or "noon" if the indicator is a "PM"? Or at the bottom, with those roles reversed, but misrepresenting the "AM/PM" indicator? It seems to me that the switching the menu between midnight/noon depending on AM/PM would be an extra complication, hard to do using some technologies, but clearer. Or is there another presentation that would be better?


Is there a usability guideline somewhere suggesting how to do this that I could refer the developers to?



Answer



There is some interesting pedantic information on the weirdness of midnight: http://en.wikipedia.org/wiki/Midnight


Specifically, technically, at midnight, it's neither am nor pm. But merely the instant of transition between the two.


Some ideas:



  • Use a 24 hour clock. Perhaps with 12 hour correlations in parenthesis:




...
10
11
12
13 (1pm)
14 (2pm)
etc




  • Perhaps indicate the am/pm with an icon as well (moon/sun) when 12 is selected as the hour to emphasize the difference




  • use a 12 hour clock, but list all 24 options





...
10 am
11 am

12 noon
1 pm
2 pm
etc...

I think I prefer the last option for a couple of reasons:



  • selecting from a drop down of 12 options vs. 24 isn't a huge burden

  • you can remove the am/pm drop down since this handles both

  • noon and midnight are very clear in this list



From Fourier Transforms to Option Values


I am trying to understand how Fourier transforms & Characteristics functions can be used to calculate option values.


However, I am having difficulty following the process that is used in several introductory papers like: Carr & Madam, Liuren Wu, Schmelze or Chourdakis (chapter 4)


In order to obtain an intuitive understanding of this method, it will be very helpful if someone could provide me with an example on how to calculate option prices using this pricing technique.


Since this is not homework, any intuitive example will be greatly appreciated.


EDIT: as a potential example, consider that we want to estimate the fair value of an European call option struck at $K = 12$ and with time to maturity $T = 2$ years. The underlying asset $S$ has initial price $S_0 = 10$ and its returns volatility is $\sigma = 0.25$. The risk free rate is $r = 0.05$.


For the previous example, the Black-Scholes equation indicates that the option fair value should be $1.07$. How can I reproduce this result using Fourier transforms?




fiction - Can I get sued for using family names/experiences?


So, I want to write a fiction story and I want to draw heavy influences from my large extended family like aunts, uncles, grandparents etc. My family has an interesting story of how they fled communism to come to the US and I would love to incorporate the many different personalities that my aunts and uncles have as well as their different stories of how they fled the country. My question is could they(uncles and aunts) or their kids(my cousins) ever sue me for using their names or stories? Or would I be better off creating different names and just using their stories instead? I'm not saying this because there is bad blood in between any of us, quite the contrary, but I do know that money can change people sometimes.(Im not saying Im going to make any money off the book, I'm just interested theoretically at what could happen should something ever happen)



Answer



I answered a similar question here.


It should be perfectly fine to use a real life point, as long as there are no legal issues with regards to it. As long as you're not attempting to damage the people involved's reputations or defaming their names - there should be no trouble.


However, if you want to be 100% sure, make sure to ask the people involved if it is okay. It is sometimes surprising how many people love the idea of someone writing a book or making some documentary about them!


validation - Disabled submit button on form vs allow submit then show errors?


We have a few different forms as part of a web-based medical application. These forms have quite a few fields - 10-20 depending on the form. Each has at least 5 or so required fields. We currently disable the save button until those required fields are all completed.


We've been debating whether it's a better user experience to make the submit button enabled by default and then display an error message (and highlight missing required fields) if the submit button is clicked before all required fields are filled out.



Any research or sound opinions on what might be better? We're leaning towards the latter approach since our forms are pretty long -- allowing them to submit then find errors might be more efficient than the cognitive load of searching through the form to see why the button isn't enabled.



Answer



If the button is merely disabled, users will



  1. Think the application is broken,

  2. Not immediately realize which fields are unfilled and

  3. Not realize the fields are unfilled until the very end, which is annoying


So, I'd suggest telling your colleagues exactly what you told us, which is that




allowing them to submit then find errors might be more efficient than the cognitive load of searching through the form to see why the button isn't enabled.



Should we disallow common passwords like "password" and "12345"?


Studies show that people can use some really "insecure" passwords. Here's Mashables worst 25 passwords of 2011 for example. To protect security on our sites (and the overall experience of less-hacked site), can we reasonably disallow common passwords such as appear on this list? Or, would users who want to use "qwerty" as their password be inconvenienced enough that it's not worth it?


Consider these two case studies and answer for both:





  1. personal security— the site retains personal information such as name, birthdate, and email (enough to spam, phish, and mess with users' credit)




  2. financial security— the site retains financial information such as credit card number (enough to rob users and completely discredit the website)




Any studies on password requirements, usability, and user experience would be great.



Answer



I don't think there is anything wrong with disallowing those common passwords, I just wouldn't advertise that you do so if it's a web-app as then a potential cracker would take those rules into account when trying to crack accounts.



What you'll find is that no matter the rules you try to put into place, users who don't care about the information their password is protecting will attempt to find the easiest way around those rules. If you make it so they can't use p@ssword, they'll use p@ssword1. Consider this paper by Dr. Rick Smith entitled "The Password Dilemma". The main sections to read there for this question would be the first three: "Strong Password Policies", "Passwords and Usability", and "Dictionary Attacks and Password Strength".


My opinion is that most people will consider financial information needing to be more secure and the user will therefore be more invested in making a strong password. However, attempting to help a user make their password stronger by providing the appropriate nudge/pressure to make it more secure is not a bad consideration either.


I think the most common practice to help promote stronger passwords is to provide a weak - medium - strong indicator for password "strength". This will allow you to educate your users as opposed to enforcing strict rules which may then be able to be learned by crackers to narrow their search. This meter concept is an arbitrary measure intended to make the user think for a moment longer about their choice of password. A sample methodology for implementing a password-strength meter is provided in this paper "Adaptive Password-Strength Meters from Markov Models".


There's some great information on the usability of passwords on baekdal.com, specifically on how they're most typically cracked.


There are a lot of studies, articles, posts, et cetera on the matter of password strength and usability. With all the above considered, I haven't personally found anything on specifically discriminating on a list of common passwords.


programming - What .NET library can I use to solve optimization problems?


I'm working with C# and I start being bored writing optimization algorithm.


Do you know any free library containing this sort of algorithms?


In particular I'm currently working with Semidefit program.




Tuesday, November 28, 2017

fonts - Why should I ever use Unicode’s special characters for Roman numerals?


This is to answer a question which arose in the comments on this question on the Unicode characters for Roman numerals:




Why is this necessary or preferred over the usual way of typing ai, ai-ai, ai-ai-ai, vee-ai, etc.?



To start from the beginning, in Unicode’s Number Forms block, there exist code points for Roman Numerals that are at first glance very similar in appearance to standard capital latin letters or combinations thereof (U+2160 – U+217F). For example, U+2165 (Roman Numeral Six) looks very much like VI (Latin Capital Letter V and Latin Capital Letter I).


Thus, the question arises why one should not use the latter to represent those digits and, e.g., type Louis VII instead of Louis Ⅶ. Obviously, using no special characters avoids compatibility issues with fonts that do not support them. But even if I know that the text will be rendered with a font that does support these characters, why should I bother using them?




Proof for non-positive semi-definite covariance matrix estimator


It is well known that the standard estimator of the covariance matrix can lose the property of being positive-semidefinite if the number of variables (e.g. number of stocks) exceeds the number of observations (e.g. trading days). I think the matrix can become singular. I have a clear idea why (inspired by the geometry of the problem) but does anybody have a short but rigorous proof for this fact?



Answer



The standard estimator of the covariance matrix is: $$\widehat{ \mathrm{cov}}(X) = \frac 1 {n-1} \sum_{i=1}^n (X_i-\bar X)(X_i-\bar X)^T,$$ where $X_i$ is the column vector containing the $i$th observation of all the observables. Each summand is an outer product of a vector with itself, i.e., a square matrix having rank at most one. Therefore $$\mathrm{rk\;}\widehat{\mathrm{cov}}(X) \le n$$ and the matrix not only can be but is always singular if $$n \lt \dim X,$$ i.e., if the number of observations is less than the number of variables.





Edit: regarding positive-semidefiniteness: $\widehat{ \mathrm{cov}}(X)$ is always positive-semidefinite because it is Gramian, even if its rank is not full. It loses the property of being positive-definite if and only if it is singular.


responsive design - What to do if more than 2 hamburger icons in nav bar?


I am building a website for each office within an agency (about 6-8 different offices). I want to make it easy for a visitor to jump to another office website when on an office website. So, each office website will have a dropdown list in a navbar that can be used to jump to a specific office page.



Problem: The ABC Network dropdown is competing against the main nav dropdown for the "P" office when the viewport changes to tablet/mobile view (examples below).


Question:



  1. How would you differentiate between the 2 navs? Should we consolidate all into one main toggle nav?


DESKTOP VIEW


Desktop view


MOBILE VIEW enter image description here




adobe photoshop - How to remove white background from multiple images?


So I received approximately 70 or so images from a customer and apparently they were all scanned. They are 4x6 prints but each one has a white background the size of a paper. How can I get rid of them en mass?




technique - How important is education for an author?


By education I do not mean to ask how important a degree in English is for an author. A literate person, without any formal education, could pen an amazing story. On the other hand, a PhD might not guarantee professional success. I want to know how education, in any field, influences the writing ability of an author. Does maturity in the writing technique and the story itself, come with being better educated? Do people having been educated in different countries than their homeland have better stories to tell due to the different life experiences they get?



Answer



Since you can only write convincingly and engagingly about things that you know, experience and knowledge are invaluable for any author. You an make up a lot, of course, but only if you understand the principles behind what you are making up. For example, you can make up how a certain person behaves, but only if you understand how people behave in general (not: on average!). If you have no experience with people, you'll invent behavior that will seem false to your readers. The same goes with everything else.


Of course no author can know everything, which is why often writing is preceded by research, which can include doing yourself what you want to describe your characters as doing, visting the places you write about, or learning the basics in a certain scholarly discipline.


If you write fiction, what you don't need to become is an expert. Most books don't go so far into the matter as to need that kind of expertise. But if you write a biography, you certainly need to be an expert for the portayed individual. Or if you write a political novel, you better understand politics better than the average person, else they will ridicule your ignorance in their reviews on Amazon.


But what all authors must understand is themselves. Critical self-reflection is a prerequisite for understanding other people, and understanding people is a prerequisite for portraying convincing characters. But I don't think that intelligence is a prerequisite for successful self-reflection. I have met many thoughful persons who didn't score high in IQ tests.




As for formal education, that's in my answer already. Going through formal education is an experience that shapes the lives of people. If you haven't gone through school, how can you understand the vast majority of people that have gone through it? On the other hand, not having gone through formal education will give you a unique perspective that the majority lack, so you can show them something they don't know.



Your life will determine what you can or cannot write about. I'm a man, and no matter how much I try, I cannot truly understand (and write about) what it means to be female in our culture. I can write female characters who go on an adventure and fall in love (because I understand adventure and love), but I cannot write a book about what it acutally means to be female.


The knowledge you gain through formal education doesn't matter. You can learn that elsewhere. School is not just about knowledge, it is about training your mind and forming your personality in a specific way. Homeschooling, or growing up on the street or as a bushman and learning from your father, the hunter, will train your mind in different ways and form a different kind of personality.


But since every child and adolescent goes through some kind of "schooling", no matter if they go through formal education or not, all have some kind of experience that will inform their writing, so which kind of "schooling" you experience does not really matter. Where people differ is wether they go through higher (formal) education, or not.


So do people who go through college or university differ from people who don't, from the perspective of being a writer? Yes and no.


Higher education, like school, is not only a way to acquire knowledge, but also an experience. It is an experience that, among other things, involves conscious thought. Compared to someone who graduates from high school and then sits down to start writing their first book, a college or university graduate has had a few more years to think.


No matter what you study, higher education has the side effect that you apply the traing of your mental muscle that you recieve there to other areas of your life. What you do with it, will depend on your personality. Some people put all their mental power into learning everything they can about comic books, others invest it in political activism, and some think about themselves and their families and their relationships to the people around them.


A person who works, does not usually have that cognitive stimulation and leisure for experimenting with it. And a person who starts writing right out of high school, does not have any adult experience at all.


Higher formal education is a valuable way to train and expand your mind – your ability to think, your power of observation and reflection –, and your writing will profit from that. It certainly is not the only way to gain that or a similar growth, but (in our culture) it is an easy and straightforward way.


I would advise you against studying literature, though. Studying literature is belly button gazing, if you want to become a writer. It will lead to literature about literature, writers writing about writing, and formal experimentation that is boring and does not sell. Physicists, lawyers, physicians, historians, and scholars from every other field that is not literature, write the best fiction, because they have a life and thoughts beyond literature.


Of course you can have experiences without studying. There are many examples of people leading exciting lives and later becoming writers. If you are the kind of person who does not plan to be a writer but to live an adventurous life, then do not study. Live, and later, maybe, turn to writing books. But if you are the average kind of person, who does not thrive on danger and hard times, then study, find a job, and somewhere along the way begin to write (or continue, if you are already writing). I can't think of a hairdresser or bricklayer writing novels, so studying seems the natural way anyway.



I don't believe in taking up a career as a writer, as you can see, at least in the realm of printed fiction. Screen writing and writing for games and such seems to work differently, but I have no insight into those fields. All that I wrote above is limited to writing novels or short stories. I think a screen or game writer is someone who has to be inside the field to progress; a novelist on the other hand usually is someone who grows outside the field and only becomes an insider with his or her first publication.


adobe photoshop - Creating a pattern from an image


I need the following image turned into a pattern that would repeat in the y-axis only. How can I make it repeat smoothly (so it actually looks like it's a pattern)?


http://i.imgur.com/HwDHaeJ.jpg


Thanks!



Answer



The idea behind creating tiled patterns is to make sure that the edges match up with each other.


Generally, it's easier to blend things that have similar texture, color, and contrast.





  1. Crop the section of the texture that you want to use for the pattern.


    Crop the image


    Working with the top half of the image, since the top and bottom edges have similar composition.




  2. Duplicate the cropped layer, we will need this later.




  3. Apply a vertical offset on the image. Filter > Other > Offset....



    3a. Make the offset equal to 50% of the image height. This will give you room to blend the image.


    3b. Also make sure to select Wrap Around under the Undefined Areas section.


    Set a vertical offset


    We only need a vertical offset to the image since we only want to repeat this image on the y-axis.


    Offset result:


    Offset result




  4. Move the duplicate layer on top of the offset image. We are going to make something to cover that offset seam.


    This is how my layer turned out using the Eraser tool with a Soft Round brush preset:



    Blend the seam


    And this is what it looks like over the offset image:


    Final image




  5. Here's a jsfiddle to show what the image looks when it's set as a background-image.




Faking a page-fold with photoshop


Do any of you happen to know of some recommended techniques in creating the effect/look that makes a page appear as though it had been folded before?


Something like this: enter image description here



Answer



It's mostly just playing with gradients until it looks right which can be tricky. Some things to pay attention for...




  • Make the sure the "print" material is bent too


    Though I don't often see it done properly, one of the things that can make bent/crumpled effects look very nice is to apply subtle transformations to the "print" on the page. For example, the image you posted has a nice fold effects with the gradient overlays, but the lines & text on it are still perfectly straight. In particular, if you look at the horizontal rule beneath the heading - the center of it has a very noticeable bend in the background but the black line is unfazed. My eyes find this very distracting.





  • Make sure your shadows look natural


    Making sure all the gradients reproduce a "natural" folding pattern also helps the effect. Pick a light-source direction and think about which direction each fold is going, and make sure the gradients are appropriate to the shadowing that would be produced. It may be easiest to fold up a regular piece of paper on your desk and study the shading in the real world.




  • Don't make the edges too sharp


    No bent piece of paper in the real world will have razor-sharp edges. Having pixel-perfect edges sometimes looks just a bit too crisp.





text - On feeds, should newer items be at the bottom or the top?


I make feeds for a living and unless I'm mixed-up, on all the feeds I can think of, from Whassapp down, of course new items appear at the top of the page, the top of the list. (I.E., the old items move down. So on a feed you push the content up with your finger to see older posts. You pull downwards to see newer posts, with ultimately the most recent at the very top. {Indeed you pull down "even further" to typically refresh.})


But it occurs to me. Text in the West grows downwards: "newer" items are, of course, at the bottom. If you're, simply, say using a text editor to make a list of notes, a diary, or TODO items, of course it "grows downwards" - the newest stuff is at the bottom, and when you add one it's at the very bottom.


So,


i) In fact are there any major examples of feeds (feed apps, social apps, social in-browser apps, etc) which indeed grow by adding on the bottom? (Newest item is on the bottom; you push up (exactly like any text at all, any typed page) to see the newest stuff at the bottom.)


ii) Has this issue been explored? Is there a reason that (unless I'm mistaken) new is always on top?


iii) In fact should the new item be at the bottom? Any obvious woes I'm missing or any thoughts?



iv) Why (what cultural, technical, historical or accidental reason) is the new-at-top seemingly dominant in feeds??


(Note that certainly on device apps, the bottom is "always there", since the window is the glass: sure, in a web browser you could maybe "not see the bottom", you tend to "see the top" of a web page: of course these days you could shape it to the local height of the page ("just like an app"). Indeed perhaps, is the only reason we now apparently traditionally put the new item on top in a app feed, that, traditionally on a web page you see the top, not the tail?)



Answer



Perhaps the most notable example of a feed where the newest items are at the bottom is forums. Although not a "feed" in the very strictest sense of the word, forums wouldn't work any other way. In my experience, whenever context demands that you have read the older stuff first (like forums), then the new content is always at the bottom.


On the other hand, this is certainly not a rule. Take text messaging applications, for example. I've never seen one where new text messages came in at the top, even though texts tend to be short and spaced out through time such that it would work perfectly fine flipped.


So I guess my point is that in things like news feeds where one item is unrelated to the next, all the user cares about what is newest, so the newest content is made prominent. But where context is necessary and the old is just as important as the new, the new stuff comes in at the bottom.


Monday, November 27, 2017

website design - How do you conquer the challenge of designing for large screen real-estate?


This question is a bit more subjective, but I'm hoping to get some new perspective. I'm so used to designing for certain screen size (typically 1024x768) that I find that size to not be a problem. Expanding the size to 1280x1024 doesn't buy you enough screen real estate to make an appreciable difference, but will give me a little more breathing room. Basically, I just expand my "grid size" and the same basic design for the slightly smaller screen still works.


However, in the last couple of projects, my clients were all using 1080p (1920x1080) screens and they wanted solutions to use as much of that real estate as possible. 1920 pixels across provides just under twice the width I am used to, and the widescreen makes some of my old go to design approaches not to work as well. The problem I'm running into is that when presented with so much space, I'm confronted with some major problems.



  • How many columns should I use? The wide-format lends itself to a 3 column split with a 2:1:1 split (i.e. the content column bigger than the other two). However, if I go with three columns what do I do with that extra column?

  • How do I make efficient use of the screen real estate? There's a temptation to put everything on the screen at once, but too much information actually makes the application harder to use. White space is important to help make sense of complex information, but too much makes related concepts look too separate.

  • I'm usually working with web applications that have complex data, and visualization and presentation is key to making sense of the raw data. When your user also has a large screen (at least 24"), some information is out of eyesight and you need to move the pointer a long distance. How do you make sure everything that's needed stays within the visual hot points?

  • Simple sites like blogs actually do better when the width is constrained, which results in a lot of wasted real estate. I kind of wonder if having the text box and the text preview side by side would be a big benefit for the admin side of that type of screen? (1:1 two-column split).



For your answers, I know almost everything in the design is "it depends". What I'm looking for is:



  • General principles you use

  • How your approach to design has changed


I'm finding that I have to retrain myself how to work with this different format. Every bump in the resolution I've worked through to date has been about 25%: 640 to 800 (25% increase), 800 to 1024 (28% increase), and 1024 to 1280 (25% increase). However, the jump from 1280 to 1920 is a good 50% increase in space--the equivalent from jumping from 640 straight to 1024. There was no commonly used middle size to help learn lessons more gradually.




To help focus the question a little bit, I had a project that was somewhat similar to Atlassian JIRA, an issue management system. There were about six different types of records the client wanted to keep, all of them could potentially be related to each other. Gathering data wasn't the core problem, although it did play a part.


The more important side of the problem was creating a system which would suggest potential relationships between the records and helped the analysts recognize patterns in the reported incidents.



There were different types of analysts that focused on the different problem domains, and due to the nature of their exploratory type of work, they didn't know what they wanted. They just knew they had to make sense of a lot of data, draw correlations, and characterize classes of issues.




(Originally asked here: https://softwareengineering.stackexchange.com/questions/45864/how-do-you-conquer-the-challenge-of-designing-for-large-screen-real-estate, but told that this might be more appropriate)




For the bounty: Stretch your minds a bit. The pat answer "Make everything bigger" has a limit to how useful the answer is. We are talking about users who have to make sense of a lot of data and find relationships between records. If I simply bump up the size on everything they are going to be very limited in what they can see on the screen--particularly because the vertical is so constrained.



Answer



The most important thing seems to me to allow views of multiple levels of detail at once and illustrate the relationships between the views. Where screen estate really kicks in, is when you can switch from one level to another by just looking at a different part of the screen, rather than clicking on something.


So first to do I think is getting multiple levels into one screen, and also use the screen estate in both relating the parts and setting them apart (and not make them too crowded or overwhelming). The relations can be made visible by higlighting items in lists and drawing boxes on pictures so you know what details you look at.


The number of columns, well, that really depends on what views you bring into the screen at the time. In more visual settings (image editing, map views) I could imagine it being one main area and make the other columns just a bit wider than usual, to make things like thumbnail view or tool details (think photoshop) less cramped. In issue tracker systems I could imagine the 'details' section of the three column layout be split up even more (either vertically or horizontally) to include things like customer details, replies or related issues.


Also something to consider is that you have more space. It is a promotion of the 'make it bigger', but one you can really use to your advantage. With wider screens, you can (for example) display recognisable thumbnails without pushing other details out of the way, or put more information side by side. (On smaller screens, I never could fit the things I wanted in the column list of my mail app, so I would just see half the subject line, or only the first part of the name.)



Also, when you have more screen estate, you can use more graphs and illustrations. They are annoying when you need to click to get to the info, and then people prefer the data over pictures only (is my experience). But if you can have both...


One more suggestion is to look into topics about data visualisation and dashboard design.


What is the smallest screen size you design for



I'm looking to make my website responsive, however this is my first foray into responsive design, and I'm pretty clueless at the moment.


I have no idea what the current state of play is with regard to screen sizes for phones, hand-held gaming machines et al, so I'd appreciate some advice on what the smallest devices are that you currently design for (in pixels). I know that there are more variables to it than this but it would be a start.




How to pick and differentiate a flat color?


When I am using Color Picker in Photoshop or Illustrator I am unable to get a Flat color. What are the things or basic points that I should keep in mind so that I am able to judge a color whether it is flat or not. Although flat color can be picked form websites such as




  1. http://flatuicolors.com/

  2. http://www.flatuicolorpicker.com/all
    e.t.c.


Picking a flat color is not my problem. I want to learn the skill needed to judge and differentiate a flat color from other.
Do all flat colors values follow a pattern ?(like specific hue and saturation).




Sunday, November 26, 2017

Saving an Adobe illustrator file as a pdf - are fonts embedded? If so, why does Adobe illustrator say I don't have the font when I open it?


If I have an Adobe Illustrator file, and I save it as a .pdf - it looks like the fonts are included in that .pdf file. (I think this because when I open the .pdf file in Reader it looks the way I expect it to.) However, when I open this same .pdf file on a different computer (or workstation) with Adobe Illustrator - Illustrator says I 'don't have the font I need'. This doesn't make sense to me because - If I can see the document correctly in reader, I would expect it to be there for Illustrator as well. Can someone explain why this is? I am asking because saving a file as a .pdf for print seems to handle most font troubles that come up - but sometimes I need to change the text in a file before I print it... I am hoping there is a way to open a .pdf so that .ai recognizes that the font is in there. But I am unsure on the details of saving as a .pdf in Illustrator, how fonts are handled, and what is possible.



Answer



Adobe is one of the big font sellers on the planet. It is a way to enforce font licensing deals.


Most people dont realize fonts cost money. A lot of money in fact. If the average user would just be able to extract fonts seamlessly from PDF files then there would be a lot less value in the font market, since now you could just copy fonts from all over the place quick and easy. Most people wouldnt see a problem with this, again, as they arent aware that fonts cost money.


So adobe wont extract the font, even though it it is in the PDF file. Though, the font may have been embedded only partially in the PDF file making it less than useful for editing. Anyway Acrobat can edit the PDF with embedded fonts.


Theres no technical reason why they couldnt do this they just dont want to, because it conflicts with their business interest.



It is a bit like adobe wont edit pdf files marked as noneditable, and wont print pdf files that are nonprintable. Theres no encryption that stops them from doing this. They just voluntarily enforce their own rules.


readability - How long should a temporary notification (toast) appear?


For our intranet application we have little notification messages (toasts) that indicate successful operations like "information saved," "logged out" etc. Most of them are not important enough to require a modal operation (like Stack Exchange's "click to close" windows) so they close automatically after 2500ms and I'm trying to make them disrupt the user as little as possible. They are however important to present as users need confirmation an action was successful as it may be part of a repetitive or complex workflow.


I want to make sure they're readable and understandable within the time frame so I was wondering if there was any research on how long it takes people to read information especially in a "pop up" style context. It's not actually a pop up window, more like SE's notification bar but it automatically goes away. If I could ballpark how long to expect reading to take it would help tune the duration of the message and the length of messages.



Answer



For what it's worth - I tried a variety of timings myself and ended up at 3200ms for a two line message of up to about 20 words. But I also place a small dot (10px diameter) to the left, which is coloured according to message type (eg red/error, blue/info, orange/warning) and which fades out over the 3200ms. When the fade gets to 100%, the message itself fades out quickly. Users said they like it because it makes the message slightly more noticeable without being too distracting and it made it less of a 'surprise' when the message disappears.


language - Spanish UX Keywords Cheat Sheet


I expect to be working on a web application within the next several months and I'd like to "shoehorn" a Spanish language version of the site. If a large enough number of Spanish language users begin using the site we'll likely hire a professional translator (or at least recruit someone who actually knows the language), but in the meantime is there a good cheat sheet I can use for common UX keywords, like "OK", "Submit", "Cancel", "Delete" and "Save"?


I know I could use an online translator, but I'm concerned the translator would not pick up on context (thus giving me a Spanish word meaning something closer to "Take" for "Accept" or "Surrender" for "Submit", etc.)


I'm not looking for a 100% solution, just something to give me the bulk of the keywords until there's enough reason to hire a real translator. This site will be in a beta development phase for a long time, I think, so we're not expecting a huge user base to start things off.



Answer



I'm Spanish, I hope I can help. I don't know any cheat sheet of common Spanish words for interfaces, but one possible solution would be to change the language preferences of one application you are familiar with (Gmail, Facebook, Twitter, Ebay) and use the expressions it uses.


Having said that, I recommend thinking carefully about the decision of translating your application. It takes an extra amount of time and money that has to be taken into account. And an interface half translated is really weird... Therefore, if your users understand English, I would recommend using this language in the first version of the application. ¡Mucha suerte!


Acceptable waiting time for users in time sensitive actions


Is there an acceptable waiting time for users when they are on banking or finance related websites after they perform an action? I expect that for important tasks users are prepared to be more patient, but if it is a bidding or auction related website then they would want to know that the transaction is immediate.


Probably the ‘gold’ standard when it comes to general website performance in relation to user behaviour: http://www.nngroup.com/articles/powers-of-10-time-scales-in-ux/




  • 0.1 second is about the limit for having the user feel that the system is reacting instantaneously, meaning that no special feedback is necessary except to display the result.

  • 1.0 second is about the limit for the user's flow of thought to stay uninterrupted, even though the user will notice the delay. Normally, no special feedback is necessary during delays of more than 0.1 but less than 1.0 second, but the user does lose the feeling of operating directly on the data.

  • 10 seconds is about the limit for keeping the user's attention focused on the dialogue. For longer delays, users will want to perform other tasks while waiting for the computer to finish, so they should be given feedback indicating when the computer expects to be done. Feedback during the delay is especially important if the response time is likely to be highly variable, since users will then not know what to expect.


The closet I can find to an industry standard benchmark is the Compuware APM Benchmarks http://www.compuware.com/en_us/application-performance-management/Benchmarks/view-benchmarks.html


The closest I can find to any actual figures are from the Best of the Web 2013 awards handed out by Compuware, which specializes in website performance benchmarking. The average response time for the winners in the brokerage category that uses a Generate Order Transaction ( includes accessing the home page, logging in, navigating to the trade page, selecting a stock, previewing the order, cancelling the order, navigating to the trade page and logging out) are:



  • response time: between 3-4 secs

  • average availability: 99.9%

  • standard deviation: between 1.5-2.2 sec



These are the figures from the server side, and usually there is about an extra second or two added to the response time in getting to the actual user device (the so-called 'last mile'). So basically all of the transactions on the websites that are regarded to be the best performing that industry are well within the 10sec barrier but a little bit more than the ideal 1sec response time. However, depending on the particular action of the user a 3sec response time would be more than acceptable.


Does anyone have experience or know of any standard measures for these types of response times?


UPDATE: The RAILs model published by Google provides another set of standard for user interaction response time, but is based on similar principles and ideas.




interaction design - Should an opened sub-menu collapse when the user opens other sub-menu?


Take for example Google Material design website, that has big sub-menus in the sidebar's menu.


The sub menus are closed on page load.


Material design
Motion
Style
Layout
...


Clicking on a menu title expands its sub-menu


Material design
Introduction
Environment
Material properties
Elevation and shadows
What's new
Motion
Style
Layout

...

When clicking on a different menu title, should the opened sub-menu collapse or not?


Option A:


Material design
Motion
Style
Color
Icons
Imagery

Typography
Writing
Layout
...

Option B:


Material design
Introduction
Environment
Material properties

Elevation and shadows
What's new
Motion
Style
Color
Icons
Imagery
Typography
Writing
Layout

...

In Option A (which might animate) the user's cursor would be over some different element after the sub-menu collapses (not good). Displays the menu in a cleaner way, without the need to scroll.


Option B does not trigger undesired actions (Option A somehow triggers an action). The user might have to scroll to see the just-opened sub-menu. The user might have to close the opened sub-menu to see clearly what he just opened.


What is the user's expectation, which option facilitates user's task?




Edit:


On a side note I just read this on Navigation patterns - expanding navigation drawer:



Selecting a collapsed section expands that level in-line, hiding all levels outside of it.




This looks like Option A. However this is not applied in the same website, that applies Option B.




fonts - Distinguishing real and faux bold and italics


Some software (such as Microsoft Word) will silently use oblique or "faux" italics and bold styles when the appropriate font variant is not available.


For italics, I've been using the test of typing Roman and italic lower case f next to each other, since most italic variants have an F that uses a descender. If I don't see a descender, it's likely that the software is faking it.


My question is:



  • Is the above test (comparing lower case f) a reliable test for true italics?

  • Is there a similar test that can be applied to bold weight?



Answer





If the font doesn't exist then you're obviously seeing faux styles.


It's often a lot easier to spot what isn't a faux style rather than what is, so look out for features that indicate a real style rather than signs of anything "faked" and compare with the regular font to spot differences, any difference in glyph shape (other than the slanting that is) will indicate real style.


Serif Typefaces


The easiest faux vs real italics to spot are those of serif typefaces. Most well designed serif typefaces are significantly different in their italic forms. They are cursive and more calligraphic. Straight serifs turn to curved "flicks" and different glyph shapes are often used.


Compare Garamond Roman and Garamond Italic and the difference is more than obvious:


Garamond Roman vs Garamond Italic


Common features to look out for:



  • Double to single-story lowercase "a".

  • Lowercase "f" with a tail


  • Different ball terminals

  • Intersection of strokes (such as Garamond's "p")

  • Curved lowercase "e"

  • Any loops or swashes (Garamond's "k" and "z" for example)


Minion, who's differences are much less pronounced than Garamond are still obvious:


Faux Italic Serif Fonts


Oblique vs Italic Sans Serif Typefaces


Often used by sans serif typefaces, oblique type is made in exactly the same way as a faux italic—by simply slanting the regular glyphs. Some typefaces will be explicitly called "Oblique" but some will still use the name Italic.


In the case of oblique typefaces your only real option is to inspect the font files themselves. As you can see, Helvetica Neue Italic—which uses an oblique design—is essentially impossible to differentiate from the faux italic:



Faux Italic Oblique Fonts


Sans serif typefaces that don't use oblique styles share much of the same differences as serif typefaces although less pronounced: single-story lowercase "a"s, curved lowercase "e", lowercase "f" with a tail. Glyphs that look the same will often be narrower too:


Faux Italic Sans Serif Fonts


Spotting Faux Bold




  • In some programs, corners will be affected by faux bold styles—either with a bevel or rounded effect. If the regular typeface has sharp corners this will be noticeable and can make your type look "fuzzy" at lower point sizes.




  • The extra weight added will usually go bellow the baseline. If you are in a situation where you can physically see the line you will notice the glyphs below the line when they should be sitting directly on it.





  • Not always as noticeable but it's worth paying attention to stroke contrasts which may be affected—genuine bold will increase the contrast where it will stay consistent with a faux style.




Faux Bold


Saturday, November 25, 2017

content management - What is the best UX to let user perform CRUD operations?


My users will work on data grids bounded to list of entities. CRUD operations can be done directly in the data grid (inline editing) or in a popups (user will click in the grid toolbar on "create" or "edit" buttons).


Which of these 2 ways is considered better UX nowadays? Is there a 3rd way which is better than these 2?




fiction - What Genre Category for a Semi-Fictional Memoir?



What genre do these types of Memoirs fall under? "Inspired by true events?" ... Is Semi-Fictional Memoir a "thing"? I definitely don't feel that "fictional autobiography" fits.


I have been writing a lot of short stories that are Memoir-ish, that are based on true events in my life. Because I don't remember every detail, I tried to make some parts of the stories obviously fictional. But, in some stories, it isn't so obvious that parts are fictional. I feel that making it obvious in some stories would be intrusive, and undermine the tone.


I am hoping that applying the proper genre label would be sufficient.



Answer



From Wikipedia:


Autofiction usually has a protagonist using the author’s name and combines autobiography with fiction. One famous author of autofiction is Margurite Duras.


export - Illustrator: Converting a letterhead design to Word


I created this letterhead for a client in Illustrator and it got approved. It now needs to get converted to a Word document for internal usage. What's the best way to make this conversion?



Answer




Save images as PNG files. Insert them into Word as a Header and/or footer. Save the Word file as a template.


ux field - What's the definition of Information Architecture?


According to Morville, Peter & Rosenfeld, Louis in their book Information Architecture for the World Wide Web (2006) 3rd edition, its this:



  • The structural design of shared information environments.

  • The combination of organization, labeling, search and navigation systems within web sites and intranets.

  • The art and science of shaping information products and experience to support usability and findability.

  • An emerging discipline and community of practice focused on bringing principles of design and architecture to the digital landscape.



These are four suggestions from the book, but is there a better one out there?



Answer



I believe that the Information Architecture Institute uses those same definitions for IA, and they are probably the most widely accepted. It's difficult to create a universal definition for IA because the need to organize information is cross-domain, and the methodology will vary between each domain. For example, you wouldn't organize a website the same way you would organize a library.


For the web, I like to think of information architecture as being very analogous to the architecture of physical structures. Both types of design seek to create a functional space, placing importance on the arrangement of doors and pathways that allow one to move through the space in a natural manner.


Yield of a risky bond


When working with risky bonds, i.e. corporate bonds, what is usually defined as the yield of such a bond? Is it the yield calculated as if the bond was riskless, or is it calculated by properly taking into account the default risk in this case? And what about (risky and riskless) floating rate notes?



Answer




As John already mentioned the formula for calculating yield to maturity is independent of any risk-related numbers. Its just the connection between coupons, time and price.


In theory, default-risk can be seen as already incorporated in the yield. The yield spread between the bond and a comparable investment without default risk is a measure for the default risk premium.


For FRNs there is no way to compute a yield since coupon payments are unknown. You can only estimate the price/yield by forecasting the interest rates at the coupon dates. But the notion of yield is the same - one just estimates the coupons first.


listview - How to list thumbs that have different sizes images


I nee help, your opinions and which options do I have to resolve my problem. Currently I'm working on a website that have a Thumb view and I'm not happy on how the items are displayed, I have something like this:


Current thumbview


So, the real problem that I am facing, is that the images loaded inside each of the thumbs may vary their sizes, there are some images higher other wider, so I decided to center each of them inside the thumb, in this way:



  • The images whose height were major than the width I centered in the X axis

  • The images whose height were minor that the width I centered in the Y axis


I made it in this way to show to the user the image correctly and not zoomed or cutted, but now the thumbs are really ugly, the view can for example look like this:



thumbs with images


The size of the images are a thing that I can't handle as I get them dinamically from some services. To be more precise, it's a capture of the list in the site:


enter image description here


The upper and down space between the images is because the size of the thumb div, so it lets that space that I really don't like, when the user hovers over the thumbs 2 buttons are displayed, so I need that the thumb be at least the enough higher to display them (this maybe could be more problematic with the images that are to wide). So, what are the recommendations to improve the UI/UX of this list? Thank you very much in advanced!



Answer



You can either get rid of the outer thumb div or size it to the same size as the actual image and put a little padding around it then use a flowing grid pattern, sometimes call a masonry layout.


Masonry Layout


Here is a source for doing this in CSS:


https://css-tricks.com/seamless-responsive-photo-grid/


grid - Displaying varying prices


The holiday accommodations my company rents out have varying prices, depending on the day of arrival and the duration of the stay. Currently, these prices are charted in a scrollable table, with on the horizontal axis all dates, and on the vertical axis the duration, in number of night ranging from 3-21. Intersections that are booked don't show a price. This has the advantage of the customer being able to see what he/she would spend to depart one day later, or stay for two more days, or start their vacation a week earlier, etc. However, this also causes a pretty large grid of prices, displaying up to 7 dates * 12 durations = 84 different prices at a time. I fear this way of displaying might scare off customers, and I'd like to a/b test a new way of displaying these prices.


How could I simplify the price display, while keeping in mind the following things?



  • Prices differ with every departure-date, and every duration.

  • Being able to see the prices of nearby durations and departures is something that has worked very well in the past, and having no fixed arrival dates is a rare thing in the holiday business.



Thanks for your input!



Answer



Perhaps you could consider a design where you have a bar-chart of prices over your period. I have seen a design like that on airline sites, and I liked it a lot. Horizontally, you'd set your arrival dates, and vertically the price. You'd start with a standard-length stay, that the user might customize. I am not sure if showing a single night would make most sense, or showing a lengthier period like a week.


mockup


download bmml source – Wireframes created with Balsamiq Mockups


Then, on hovering the bar representing a day, you could show an overlay or an area below the graph that shows prices for the different lengths of stay starting at that date, perhaps with both a total and a price-per-night for each of the stay lengths.


mockup


download bmml source


That way, you avoid drowning your price page in numbers.


Friday, November 24, 2017

navigation - Starting Instant Search as you type


This is something I've implemented in a Game Library application, the ability to type a letter or a number and have the search box go instantly into focus and search through your library as you type. So basically no matter what you are doing in this library as soon as you press an alpha or numeric key instant search goes into action. It's fast (instant) and snappy etc.


Here is my problem, users can select and deselect game icons (which represent games in the library), I want when a game is selected to be able to use WASD keys to navigate as if I were to use the arrow keys, this would mean disabling the instant search feature, but would it be OK to have keys other then W,A,S,D launch the search box knowing that 80% of the time in the library a game would be selected and that there is a 4/32 chance that a game would start with the letter W,A,S,D?


It's a bit tricky question and I've been debating with my partner whether to have instant search completely disabled when a game is selected OR have every key other then WASD still launch the instant search.




Thursday, November 23, 2017

visual design - Best form element to indicate level of completeness of a task?


For example, if the user is prompted how long they have spent playing a videogame, with the options being:



  • I have played it

  • I have completed it

  • I have mastered it


Instead of a select list or radio group, would a slider powered by JS be the best option?


For example:



enter image description here



Answer



There are two questions two answer here...


1. What do you need to do with the data?


It is important to keep in mind what data you are trying to get from a user. If you are trying to get their subjective opinion on how they are through a game, a 1-100 scale, using a free-sliding slider input, could give you a more in-depth idea as to what they are thinking.


2. What is the most intuitive user interaction?


I think what is successful about the method you showed is that the position of the options gives some context to the user. It shows a progression; least to greatest amount of time, left to right. It makes sense. More specifically it makes more sense than a list of radio options top to bottom. I'm assuming you planned on the slider snapping to one of the three positions.


Free-sliding Slider Input


I would say if you are going to make it free sliding that it might be more intuitive to just label the 2 ends; something like "Tried it out -> Dominated every level".


Generating a series of colors between two colors


Given a start color and an end color, is it possible to algorithmically generate a range of colors between them? For example, given the light and dark shades of blue/gray at the start and end of the image below, how might I generate the intermediate shades?


enter image description here


One possible solution I am considering is to create a gradient from the two colors and then sample the color at equidistant points along that gradient. Is that likely to be the best approach?



Answer



This is called color interpolation. It is what gradients do under the hood. You can do so using a variety of means and methods, and exactly how the results are interpolated depends on the method.


I commonly do this for web projects using JavaScript so that I can change colors dynamically, such as in this music visualizer. A JavaScript implementation that has a very straightforward method of linear interpolation using RGB, pulled from the example above, is as follows:



// Returns a single rgb color interpolation between given rgb color
// based on the factor given; via https://codepen.io/njmcode/pen/axoyD?editors=0010

function interpolateColor(color1, color2, factor) {
if (arguments.length < 3) {
factor = 0.5;
}
var result = color1.slice();
for (var i = 0; i < 3; i++) {
result[i] = Math.round(result[i] + factor * (color2[i] - color1[i]));
}
return result;
};

// My function to interpolate between two colors completely, returning an array
function interpolateColors(color1, color2, steps) {
var stepFactor = 1 / (steps - 1),
interpolatedColorArray = [];

color1 = color1.match(/\d+/g).map(Number);
color2 = color2.match(/\d+/g).map(Number);

for(var i = 0; i < steps; i++) {
interpolatedColorArray.push(interpolateColor(color1, color2, stepFactor * i));

}

return interpolatedColorArray;
}

Which is used like so and returns an array of the interpolated colors:


var colorArray = interpolateColors("rgb(94, 79, 162)", "rgb(247, 148, 89)", 5);



You can also find PhotoShop (and likely other program) extensions for doing color interpolation. However, you might want to check to make sure the method of interpolation is the same one that you desire, as you can use any function to interpolate based on.



capm - "Risk" Factor vs Double Sorts


With regards to a cross-sectional asset pricing (stocks) study, I am testing if one variable can explain another. One common approach to do this, is to use the double-sorting portfolio technique (sort on variable a into portfolios, then dependent on a - sort b into portfolio). This approach seems to be adequate for such a problem, if you have a large sample so that you get reasonable amount of dispersion in your sort variables.


Another approach I have seen in the literature is to create factors of your preferred explanatory variables by using the Fama French factor methodology (HML,SML etc), then sort you portfolios on the first variable (the variable you would like to explain) and run time series regression of a Fama French three factor model (or CAPM) augmented with your new factor.


I am wonder if there are any arguments for performing the second over the first approach? Could these approaches complement each other,




editing - Superpowers in Writing - Cool for the sake of cool


I originally started planning/writing a short story that was more or less based on a few popular trends in YA/Sci-Fi writing (interstellar travel, superpowers, etc) just as an exercise to force myself out of a particularly nasty bout of writer's block - I was very much okay with it having common cliches or tropes. After working on it for a while though, I decided I wanted to try fleshing it out into a longer, more complex work for young adults, so I went back to the original outlines to do a bit of editing.


One thing I had spent some time developing was a system of superpowers exhibited by a portion of the populace within the text. On the lower end of the spectrum, things like telepathy were present and on the higher end there were more complex, dramatic powers, such as electrokinesis or something.


Although they do serve a narrative purpose, I could eliminate the high spectrum abilities and the plot would still be relatively intact, save for some details that would need to be rewritten; the only real value they have is being showy, or cool, abilities. If anything, big dramatic powers like that can remove some of the work's believability. Keeping them in would simply be for the sake of 'coolness,' and to appeal to the reader - which isn't an inherently bad thing.


So, if an aspect of the narrative is easily replaceable/removable, should I do so? Or is the value those details add, though somewhat superficial, worth retaining?




Wednesday, November 22, 2017

What makes a good form?


I've recently been given the challenge to create a preferably 'fun and engaging'-form, consisting of about 40-50 fields. The form consists of four parts, Employee-contact-info, Employment-description, Competency, and Experience.


I suspect the 'fun and engaging'-bit can be dropped, but how can I make the form as painless as possible to fill in?


I have no prior experience with designing for good user experience, so any thoughts or resources on how to tackle this kind of challenge is appreciated.



I've already found this describing some methods to make forms as good as possible.



Answer



A good place to start is Luke Wroblewski and his various writings on form design


eg http://www.lukew.com/presos/preso.asp?22


But to add: From my experience building hundreds of forms, I can recommend the following:



  1. Minimise the number of fields in the system. This might require a bit of to and fro between you and the business analyst + a little bit extra user research but you'll be amazed at how many superfluous fields there might be.

  2. Clear path to completion: arrange fields and field descriptions in a way that the eye is led down the screen to the call to action buttons.

  3. If there are compulsory fields mark them clearly.

  4. Validate fields as the user types not after submit; offer in-line instructions


  5. If you have a stack of fields, either tab them into discrete sections (like you indicate) or walk the user through a sequence of pages to final completion. edit: tabs won't work for sequential information or when there is compulsory information in each tab. It is a good approach, I have found, for containing different types of content in a system that the user updates or uses over a period of time.


  6. Progressive disclosure. I allude to this is in 5). This is a way of avoiding cognitive burden or information overload. Put simply, present information in a series of simple steps instead of one big whole.




  7. Break up longer forms into visually distinct regions. This allows you to group slightly different field sets together and will help the user build a mental model of the system, it is also a way of giving the impression that the system is less burdensome than it really is (again, this could be argued to be a type of progressive disclosure).




Uncertain volatility


Recently, I have encountered something called "uncertain volatility". Is it a popular concept in QF? Do practitioners use it nowadays? What are its pros and cons compared to e.g more familiar stochastic volatility models?



Answer



It is definitely used in practice:




  • It affords a tractable way of pricing in a skew that is easier understood

  • Avellaneda proves that a derivative priced under any stochastic volatility process that is bounded by (sigma_min, sigma_max) will produce a cheaper price than under UVM

  • It is easily implemented into any PDE pricer at no calc time cost


Edit: just to challenge myself on third bullet point. Given how UVM has two vols, if you are using Euler (i.e. conditionally stable, first-order accuracy) you need to use the larger of the vols for the spatial step size to remain stable. This is not ideal for reasons of accuracy.


Rather than move to ADI (unconditionally stable, second-order) which is not simple to implement, i am a strong pusher of ADE (alternate direction explicit) which achieves the same stability and accuracy ADI but with the code- and computation-complexity of two passes of an Euler discretisation. Look up ADE by Daniel Duffy if of interest.


Tuesday, November 21, 2017

options - How to shock the IV surface w.r.t VIX and keep AOA


I have to compute the sensitivity of a set of option prices on a single sotck (range of tenor is over the whole surface) to an increase of 100% in the VIX.. and I am trying to get to the most reasonable way to do so. (The risk model in question only considers one source of randomness for IV).



The only way I can think about is to compare the volatility of the ATM IV of my single stock to the vola of the VIX, and use this to scale the shock in the VIX to a shock in the ATM IV of my stock (and thus assuming a correlation of 1, which is the assumption in the model since the VIX is normally distributed in the model). For concretness, say that this corresponds to a shock of $(1 + 0.75)$ for the (30-day) ATM IV of my single stock.


However, once I have a shock in the (30-day) ATM IV, how can I make it into a sensible shock of the whole IV surface (while preserving that it is free of static arbitrage)?


So the two questions (I am more interested in the second as I can always read and do some empirical studies to understand better the first one):




  1. How do I translate a shock in the 30 day ATM IV to a shock in the whole ATM slice of my surface?




  2. How does this new set of ATM IVs influence the whole surface in a way that preserves Absence Of Static Arbitrage (AOSA)?





In Gatheral's SSVI model, it seems to be possible solve 2. by only changing the ATM variance (in our example, we would e.g. define $\tilde{\theta}_t := \theta_t \times 1.75.$ This would not change absence of static arbitrage conditions as long as the shocked ATM variance $\tilde{\theta}_t$ is still an increasing function of time.


Also, in general absence of calendar-spread arbitrage should be conserved by a vertical shift of the whole surface. However, it does not seem to necessarily keep absence of butterfly arbitrage.


I would be glad to have some hints and experience on this one. Particularly, is the shocked surface that I obtain meaningful? Do I have any chance with something else than SSVI? Does it make sense to shift the whole surface upwards?


An important note is that I am not interested into looking at the "local" (in time) dynamics of the surface as this sensitivity is used for longer term considerations. So the main requirement here is robustness and stability.




copyright - Repeat client is suddenly demanding intellectual property rights!



A fairly sizable client whom I've done a few jobs for over the past several years has recently contacted me for a new job. We have never had a contract for any of the work I've done for them (I'm a freelance designer). In his most recent email, he said:



"By the way, I am requiring that all files in their native form belong to [my company] and are to be delivered to me upon completion of the project. The files must not be password protected and are to be in their 'collected-for-output' form before payment will be made. I consider what we pay for to be the intellectual property of [my company]."



Aside from the fact that this is a little insulting (considering I've held nothing hostage, have been perfectly civil, and complied with every request I've ever received from any client I've had, including providing original working files), I understand that this is not standard practice... Most designers, it seems, do not hand over copyrights or intellectual rights to a design. But I don't feel that it's worth losing a fairly good client over something that may make him feel I'm somehow taking advantage of him. (The designs I do for them are mostly advertisements, flyers, small brochures, etc.)


What would you do? What do you recommend?




usability study - How to discover what users NEED and not what they WANT?


I have been thinking a lot about my favorite quote from Henry Ford:



If I asked people what they wanted, they would have said 'Faster Horses'. -Henry Ford



The trouble I have been having is that I know how to make something usable, but I am an innovator at heart, I have to be trying something new.


So what is the way to discover what users NEED and not what they just WANT?


If I do a user test the way I do now, I get their reactions, wants, and desires, which are rather predictable 9 times out of 10. But what I am having trouble with is digging out their needs.



Answer



Make sure that you focus on goals.



Don't ask what your users want or need in terms of functionality or form. Find out what they need (or want) to achieve .. that way the parameters you use to define and solve the problem will be much clearer and focused.


Questions to ask your users might run along the lines of;



  • what they need to achieve.

  • how they currently achieve 'x'


then



  • moving on to find out what makes current methods difficult.



Don't carry out user research for solutions - research problems


Monday, November 20, 2017

How do you explain the details of something technical to a non-technical audience?


When writing about technical topics it is often difficult to get across the complexity of a topic without getting "stuck in the weeds" and ultimately leaving the audience confused or disinterested. Particularly when the audience lacks the necessary background to explain the topic in it's own terms (e.g. explaining the usage of a certain type of cryptography to management or end-users).


What techniques can you use to help explain the important parts of a topic, and possibly introducing the relevant jargon, while keeping such an audience engaged?



Answer




When explaining concepts of any kind to an audience unfamiliar with the knowledge domain, the following methods are highly effective:



  • analogy & metaphor - compare (albeit inexactly) what this thing does to how that thing does whatever (in computer software, hardware, and services (among other fields), there is the ever-present "car comparison")

  • stories - humans are highly story-oriented beings (it's used in selling, teaching, programming, history, math, etc etc)

  • the three pitches (there are variations, like this one, too):

    • 30 second :: aka "elevator pitch" - get someone excited enough to want to keep listening/reading

    • 300 second :: you've got their attention, don't lose it; go into a little more detail - but don't overwhelm

    • 30 minute :: you really want people to buy-into what you're telling them





Communication is like selling - it's all about return on investment. And ROI is all based on understanding abstractions (and how they leak). You need to give the reader/listener enough of a promise they're going to get value at least proportional to the time spent consuming what you're trying to convey that they want to stick around.


Guy Kawasaki promulgates the "10/20/30 Rule of PowerPoint" (in direct relation to pitching to venture capitalists, but the general premise carries into most other realms well, too):



  • no more than 10 slides

  • no more than 20 minutes

  • no font smaller than size 30


If you cannot convey the core basics of what you want your audience to "get" in a few minutes with [the equivalent of] a few bullet points in an easily-followed (ie "large font") manner, you're [probably] not going to be very successful in "communicating".



Once you've accomplished the levels of "hook" you need to get your audience to want to continue through, keep it up: there will be boring aspects of what you need to convey - don't skip them, don't dwell on them too long, don't lie about them, and don't over-simplify them - but try to make them as short and interesting as you can.


Is it bad practice to make people fill out forms to download company whitepapers?


Its useful for the company to know name/email/company of the person requesting the download but isn't it more of a barrier that is not good for UX and puts people off?



Answer



That depends. Which is greater: the company's motivation to get people to read whitepapers in which they are not that interested in? Or the user's motivation to read the company's whitepapers which are highly recommended must-reads?


The difficulty or inconvenience of the barrier must be appropriate to the motivation of the user and the value of what is behind the barrier.


With regard to the UX topic: filling out forms is, generally speaking, crappy user experience, regardless, and you know it.


If the material really is valuable, though, I would not mind. Say some renowned author suddenly makes a free electronic copy of a 25 year old classic textbook available on his website in PDF, and he only requests that you grace the guestbook with your johnny@walker.com. How could anyone object.


exotics - What Positions on an Underlier CANNOT be Hedged with Vanillas?



Say I have infinite precision of strikes $K$ (continuous world $dk$) and expirations $T$ (continuous $dT$) all with liquidity (so no practical limitations). What positions in an underlying can't be replicated? I'm under the impression I can replicate any European payoff, so if I had infinite expirations I could replicate really any position.



Answer



Any non path dependent European type payoff $f(S_T)$ can be replicated in a model independent way with vanilla calls and puts provided $f$ is twice differentiable (in the distribution sense). This is a consequence of the Carr-Madan formula.


delta - Implied volatility interview question



If an implied volatility of an out of the money call option goes to infinity,what happens to the delta of the said call option?



Answer




The Black-Scholes delta: $$\partial_SC=N\left(\dfrac{\ln\left(\frac{S_0}{K}\right) +(r - q + \frac{1}{2}\sigma^2)(T - t)}{\sigma\sqrt{T - t}}\right)$$ As you can see this delta would go to$1$ if $\sigma\to\infty$ (and $t

risk - What is the best way to "fix" a covariance matrix that is not positive semi-definite?


I have a sample covariance matrix of S&P 500 security returns where the smallest k-th eigenvalues are negative and quite small (reflecting noise and some high correlations in the matrix).


I am performing some operations on the covariance matrix and this matrix must be positive definite. What is the best way to "fix" the covariance matrix? (For what it's worth, I intend to take the inverse of the covariance matrix.)



One approach proposed by Rebonato (1999) is to decompose the covariance matrix into its eigenvectors and eigenvalues, set the negative eigenvalues to 0 or (0+epsilon), and then rebuild the covariance matrix. The issue I have with this method is that:




  1. the trace of the original matrix is not preserved, and




  2. the method ignores the idea of level repulsion in random matrices (i.e. that eigenvalues are not close to each other).




Higham (2001) uses an optimization procedure to find the nearest correlation matrix that is positive semi-definite. Grubisic and Pietersz (2003) have a geometric method they claim outperforms the Higham technique. Incidentally, some more recent twists on Rebonato's paper are Kercheval (2009) and Rapisardo (2006) who build off of Rebonato with a geometric approach.



A critical point is that the resulting matrix may not be singular (which can be the case when using optimization methods).


What is the best way to transform a covariance matrix into a positive definite covariance matrix?


UPDATE: Perhaps another angle of attack is to test whether a security is linearly dependent on a combination of securities and removing the offender.



Answer



Nick Higham's specialty is algorithms to find the nearest correlation matrix. His older work involved increased performance (in order-of-convergence terms) of techniques that successively projected a nearly-positive-semi-definite matrix onto the positive semidefinite space.


Perhaps even more interesting, from the practitioner point of view, is his extension to the case of correlation matrices with factor model structures. The best place to look for this work is probably the PhD thesis paper by his doctoral student Ruediger Borsdorf.


Higham's blog entry covers his work up to 2013 pretty well.


Sunday, November 19, 2017

registration - Should (and how should I) I use email addresses for login without validating them?


So that users don't have to remember a username, my webapp doesn't ask users to enter one (accounts are private and there are no profiles or user-generated content). However, I would also prefer not to send users a confirmation email when they sign up, since I don't use their email addresses to send them things (except when they reset their password).


However, I recognise this could lead to problems if someone signs up with the wrong email and then the person that really owns wants to register. What is the best way to handle this?



Answer



My observation is it seems like you are trying to throw one stone at a lot of birds.


You mentioned you don't use the email address "except when they reset their password", you in fact mean you are using it and it is important that no user claim access to an email which they don't own. This should require an email validation.


You also mentioned you don't want users to have to remember a separate username from the email address, which seems like a worthwhile goal. You could try to integrate Oauth from other popular services like facebook or google as a way to reduce/simplify the process for some users, depending on their comfort level with shared sign-in.


stroke - Add thick outline to existing artwork in Illustrator



I have some vector images they I need to add a thick outline similar to the image below.


example of outline


Is this possible to do quickly and easily in Illustrator?


Note : I have permission/licence to edit and publish the images.




technique - How credible is wikipedia?

I understand that this question relates more to wikipedia than it does writing but... If I was going to use wikipedia for a source for a res...