incrediBILL - 4:33 pm on Oct 25, 2005 (gmt 0)

eCPM shows how AdSense is performing in comparison to other revenue sources

I don't think Google wants people the see the average CPC as most would toss AdSense seeing such little numbers and the eCPM gives you a nice false sense of CPM earnings.

eCPM is really quite meaningless noise if you don't pay attention as the example below shows you can get misleading information as $0.40 earnings can be represented as all sorts of crazy eCPM.

2 impressions, 2 clicks, @ $0.20 CPC = $200 eCPM
100 impressions, 2 clicks, @ $0.20 CPC = $4.00 eCPM
1000 impressions, 2 clicks, @ $0.20 CPC = $0.40 eCPM

Give me just one new column, an AVERAGE CPC and show me that the clicks are worth about $0.20 each which is a non-fantasy number based on the reality of your clicks, not what 'might' happen with a thousand impressions.

Basing a marketing decision on eCPM only makes sense if the same ads keep appearing that are generating the clicks as it's the CTR that makes your eCPM and nothing more.