New Top Selling Cameras snapshot posted
It is important to note that there is limited scope of what one can derive out of these. These are useful in seeing over-arching trends and momentum, but they are not detailed enough to make bold statements about Camera X vs Camera Y or Brand X or Brand Y by simply looking at a couple of data snapshots.
So when you see websites or blogs make dramatic statements based on a snapshot of the Amazon Best Sellers lists, like Canon EOS-M has taken over the US market or the Olympus E-M5 rules the world, take it with a few lakes of sea salt. Here is an example of how to badly interpret this data at tech.radar.
The Amazon best sellers lists are market-driven, new pre-orders, new releases, Gold Box deals, discounts, special promotions, going in or out of stock, and the like cause cameras to spike upwards/downwards. Amazon is one of only a small number of retailers that make new cameras available for pre-order almost immediately after their initial announcement, so new pre-orders spike high initially.
Another misconception people have is that these are permanent Best Sellers lists. They are not. Amazon uses a secret weighing-average algorithm of sorts (based on ten years of black box observations of these) in order to produce meaningful data. The statement "updated hourly" is also misunderstood. It doesn't mean the best seller lists are reconstructed hourly, but rather, new data is added to the mix on an hourly basis. If these were reconstructed on an hourly basis, there would be a lot more variance between hourly snapshots. We humans may be sheep, but we are not sheep enough to buy cameras at very similar ratios hour after hour, day or night, weekday or weekend or holiday :)