The signal is weak but extremely detectable. It's exactly like the signal for a positive response; in general, click through rates for various things are aroun

The signal is weak but extremely detectable. It's exactly like the signal for a positive response; in general, click through rates for various things are around one or two tenths of a percent. If Ad A is getting a tenth of a percent and Ad B is getting two tenths of a percent, Ad B is clearly way better. If 99.5% of people give negative feedback for Ad A, and 99.8% of people give negative feedback for Ad B, then Ad A is clearly way better.