Every so often, the question comes up among interaction designers and usability professionals regarding whether alphabetical order is a logical order. (See, for example, the February 2009 discussion on the Interaction Design list.) We’ve all seen numerous lists that appear in alphabetical order (and in which it makes sense): country, state, surname, street name, auto manufacturer. We’ve also seen many that do not: month, day of week, browser history, File menu.
Alphabetical order is NOT a logical order. It may be the best order for a group of choices — i.e., it may be logical to use alphabetical order — but that does not make the order itself a “logical” order. It is only a predictable way of ordering a set that has no intrinsic logical order.
Don’t get me wrong; predictable is good. And sometimes — e.g., in the situations mentioned above — alphabetical order is the most predictable order.
But sometimes it is not, and yesterday I ran across a perfect example. Consider the figure at right. This is a list of car sizes in the preferences area of a travel application. Does the list look logical to you? I can never remember whether “economy” is smaller than “compact” or vice versa; and what in the world is “special”? I submit that size is the logical order for a choice of sizes (duh!).
Similarly, sequence is the logical order for a choice of months or days of the week. (Would you suggest putting April first? I didn’t think so.)
The objective is to choose an order that helps people find the option they seek and (if they aren’t sure) to help them identify the right option. Ordering the car size list by size would do both.
Are you listening, Carlson Wagonlit?