sort - Filtering vs. Sorting?

I'm creating a e-commerce site that will have different experiences for consumers and business owners. We're designing the business interface to allow them to quickly research existing and future trends. We're currently thinking a table would be familiar to the user, and would allow them to print and export to Excel. There's 9 criteria that could be filtered or sorted.

Are there any best practices or rules of thumb when deciding what to filter and what to sort? Or to allow both?

Answer

When your values are on a nominal scale (names without an inherent order except alphabetical - e.g. "phones; appliances; laptops"), it makes more sense to filter, because sorting is basically meaningless - they have no real order. The exception to this is when you have a very large number of different values, which aren't repetitive, e.g. Names. In that case filtering is just not helpful, since in order to choose a value to filter you need to go through the same long list of values as you'd have if you wanted to locate that value in the table itself.

Numerical values with a meaningful order can be both sorted and filtered, it depends on the data. For example, an "exact price" column should be sorted, not filtered - because if you're interested in items that cost $200, then you're probably equally interested in those costing $190-$210, the 200 is just an anchor, and you wouldn't want to hide those similar products. Another good example is a "file size" column. But a column like "price range" could be both sorted and filtered - if you're interested in items costing $200-$300, then you may or may not want to see items in the $100-$200 and $300-$400 categories.

Columns where the user is likely to look for the minimum or maximum value are sorted, because then you get your answer with one or two clicks, and filtering would take as much work as locating the answer manually.

Columns containing a few broad categories (movie ratings on 1-5 scale on a large set) make more sense filtered, because if you have a hundred movies for each rating, then most of the time you'll be looking within category in any case, and only in the beginning or the end of the category will you see its neighbors on one side. So sorting doesn't help you, and it just makes it harder to locate the category you're looking for.

In short, the more different values you have, the more sense it makes to sort.