Recently I was on the CitiMortgage website (www.citimortgage.com) and noticed a poor design decision in the date selector. The company policy prevents you from picking a date past the 16th of the month. The drop down list to select a date, however, presents the user with all date of the current month but will show an error message if the user selects any date past the 16th. Why even present the user with those options?
A couple weeks ago, I was checking out Google Finance and noticed something scary. One of two things had just occurred; either the whole world just went broke or (slightly more likely) the web service call to retrieve the data had failed or timeout.
While the scenario was quickly fixed by refreshing the page, these are the usability points that are commonly overlooked when designing for UX. What should happen in case of failure? In this case, the default value that’s used is a 0 (zero). When dealing with numeric values, I prefer to show “N/A” or “NaN” if the audience is mathematically inclined.