Online Advertising Click-Thru Rates, Revisited

A couple years ago, I wrote Online Advertisements and Statistical Analysis, in which I did my best to show that a past study of online advertising click-thru rates (CTRs) wasn’t worth the pixels it was printed on.

About a week ago, my wife and I were visiting friends, and I found myself in a room with 3 neuroscientists. The topic of statistics came up, and I managed to insert into conversation my small triumph in analyzing the click-thru study and determining both a confidence interval and the number of tests that would need to be run in order to have a meaningful confidence interval. “Sure,” one of the scientists says, “but what you should really do instead is a chi-square test for goodness-of-fit.”
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