Jeff Sauro • December 14, 2011
Completion rates are the gateway metric.If users can’t complete tasks on a website, not much else matters. The only thing worse than users failing a task is users failing a task and thinking they’ve completed it successfully. This is a disaster.The term was made popular by Gerry McGovern and disasters are anathema to websites and software.
Have you ever bought the wrong product or found out later you got the wrong information like the value of a car, the shipping costs or the delivery time? If so then you know how both frustrating and inconvenient it can be. The most effective way of measuring disasters is to collect binary completion rates (pass and fail) and ask users how confident they were they completed the task successfully. I use a single 7 point item to measure confidence (1= Not at all confident and 7 = Extremely Confident) but you could use a 5, 9 or 11 point scale too. Disasters are when users fail the task and yet report they are extremely confident they completed it successfully (e.g. 7’s on a 7 point scale). [see Article]