Jun 21, 2011
In Academia, people who study IR have historically discussed “relevancy” in terms of “Precision vs Recall” (If these terms aren’t familiar to you, then I highly suggest reading the link) but in my experience, those kinds of metrics are just the starting point. While users tend to care that your “Recall” is good (results shouldn’t be missing), “Precision” is is usually less important then “ordering” — Most users (understandably) want the “best” results to come first, and don’t care about the total number of results.