I've noticed a definite pattern when looking at AdSense reports for the current day:
My Effective CPM drops throughout the day. By the end of the day, it's about 2/3 what it is at the start.
This happens just about every day, and the numbers of impressions and clicks are high enough that it's not just noise.
I'm guessing it's because people from different time zones access different parts of our site at different times of day, and the early people click on more high-paying ads than the later people.
Has anyone noticed a similar effect? Anyone seeing the opposite? If the above theory is correct, I'd expect to see some variation among people in this forum, including quite a few whose Efffective CPM rises during each day.
Sometimes it goes up during the day, and sometimes it goes down. AdSense stats don't always update at the same time (i.e., impressions may jump faster than clicks, or vice versa), so you can't take the numbers as gospel until the day is over--although they do tend to settle down by evening.
My CPM was huge Monday morning after a much lower than normal weekend but then ended normal at the end of the day. I was tracking to a record day but it ended up only a little above average. The only explaination I see is Adsense giving back some clicks that morning it had held for whatever reason over the very slow weekend I had.