What's a good test?

[Fish_Texas]

How long should a test be after changing ad placement, color, size, etc?
How long does it take before Adsense recognizes the change and adjusts the CPC rates up or down?

Feedback from your testing please...
Thanks Fish Texas

[Quadrille]

Depends on your site.

If you have a million visits a day, then changes should show an effect over about 9.45 hours ;) - but if you have 50 visitors a day, then you'll need to give it a month or more.

[nomis5]

At 10,000 a day I seem to see an almost instantaneous effect. I judge the effect by looking at the eCPM for the new or changed adblock. I'm not clear why a million visits per day (as noted in previous post) would take hours.

[Quadrille]

Note the smiley face and the exact number of hours.

I was merely pointing out that it varies with visitor numbers.

[nomis5]

I did see the smiley! But it interested me what you said. Even at 50 visitors a day wouldn't the effect be noticeble within a day? Or is there some way that at 50 a day Google would serve the ads differently to a million a day site.?

[Quadrille]

With a small number of visitors a day, you would see a big vaiation in click patters. Some days zero; others quite high.

With a busier site, or a number of days, the total number of visits would tend to even out the 'chance' effects, enabling you to see the 'real' effects of your changes.

Even with a very busy site, a small change in Adsense design might give misleading results if you sampled too small a time frame.

there's also the possibility - with every site that gets repeat visitors - that a change will encourage clicks 'for changes sake', and in the longer term, the previous design may have been a better bet.

So - unless you change frequently and use the chnage to prod your regulars, it may be better to let the new style 'bed down' for a while before making a comparison.

[Fish_Texas]

Thanks for your feedback, (On this site, visitors are less than 1,000 a day, all SE organic, 20% return visitors...Change made 2 days ago)
I do notice a much higher eCPM and CPC in the morning, but by the end of the day it's back to where I started before the changes.
Perhaps I need to let the dust settle before I draw any conclusions.
Fish Texas