Over this last week, my clicks on the same site, and really the same ads have dropped from mid to high $0.XX to the low $0.0X Any idea why?
A week isn't really that long of a time, If it continues happening next week too then you have a real problem.
Welcome to supply and demand. More writers on your topic = more supply of writers = lower paying ads. Fewer advertisers on your topic = more demand for paying ads = lower paying ads Be thankful for this. It flushes out the non-committed in the market, giving those sticking to it a brighter future.
Well, the keyword for the ads is 'Notebook Computers' or similar so I would presume that dell is paying more than 3 cents per click.
Why should they pay more? There are 62,200,000 sites off of Google when searching for that term. There are a limited number of ads for everyone to get access to. When that much competition for the same keywords is out there, expect to get very little per click. I also have seen that these common topics tend to pay more the longer your history is with AdSense. For whatever reason, traffic + history seems to really help my eCPM on the same topics. My best topic is one that paid nothing when I started (around $0.01 per click) but now pays very nicely, even though there are hundreds of people with similar (and short-lived) sites.
I monitor my daily average clicks rates and there is absolutely no consistency from one day to the next, specific days of the week, or from one week to the next. The changes seem to reflect the mix of advertisers, their ever changing budgets, the pages which attract visitors on any given day, and the way people act upon the ads they visit. It could even involve time of day. Over a 30 day period my average daily click rate can vary by 2.5 times from the lowest to the highest day. I have had rates stay high for a couple of weeks, go low for a couple of weeks, and go up again. And repeat.