My CPM has been going downhill for the past couple of days, after being steady for a few weeks. This just seems strange because the content on the site has not changed, and the ads that are displayed all seem to be relatively similar to the ones that appeared when my CPM was high. I was wondering if there is any particular reason why the CPM would start to go down, or if it is just random. Could it be possible that I've been given lower paying ads because I haven't updated in a few days?
Google is like that, for me cpm fluctuates from .80 to 1.50 and that is on ~50k pageviews. Get used to the randomness