Adsense Channel Statistics - is one channel really better than others?

Using statistical techniques to help decide if one channel is best

[nubbin]

Hi all,

I have been using channels to compare the effect of different ad positions on CTR etc.

I have been running the comparison on a random sample of about 200 pages for each channel, for about 3 weeks. Page impressions on each channel are about 600, and CTRs vary by a factor of 4.

So it appears one ad position is much better than the other ones.

A long time ago in a distant galaxy I used to be OK with statistical tools, but now I can't remember what technique I could use to see if my results are statistically significant. I.e. I have run the tests long enough to prove say "80% of the time channel A has a higher CTR than Channel B"

Please can someone remind me what statistical technique I could use to do this?

Thanks.

[GaryS]

Standard Deviation.

[en.wikipedia.org...]