Higher impressions correlating with a lower Adsense CPC

[MarathonMan]

I recently noticed an interesting correlation between my rising site traffic and CPC, made especially obvious with the new CPC metrics included in the Adsense interface.

In several of my sites which have gained massive upswings in organic traffic over the last few months, as my pageviews (and thus ad impressions) increased, my CPC got steadily lower while my CTR remained steady.

I didn't make any significant changes to my content during that time period, and the visitors are all of the same quality as the ones I was getting before. Has anyone else noticed this pattern with their traffic, and does anyone know what could be the cause?

[sunia]

no rather i noticed a different type of situation that when your ctr is low then your ecpm and finally cpc will also be low........