Comment by barefoot

13 years ago

Exactly what I was thinking. What are we missing?

What was meant was: If there is a period of time when you get a lot of visits, lots of clicks, and abnormally high CTR. This could happen due to external factors, for example if make the front page of HN. Over time, this effect will vanish, but you will be stuck with high CTR estimates for the design that was in place when this happened for a long time.