visitor must scroll to see a CPM ad to be counted?

[sallam]

Say a CPM leaderboard is placed in my page footer, and a visitor didn't scroll down to that part. Will it still count in CPM impressions? does the adsense js realize that somehow? or does it count impressions only when the visitor actually scrolls down to that leaderboard at the bottom of page?

[Hobbs]

There is no way to do that on the web except for onmouseover, to answer your question, no, a page impression with an ad in it is an ad impression no matter what the visitor window size is and regardless of scrolling.