Understanding feed count fluctuations

The Feedburner users out there will probably have already noticed the fluctuations that their feed count suffer over the time. Moreover, if you pay attention you will notice that during week days when you pump many posts the feed count will peak, while on weekends and on days that you do not post that number will decline (sometimes heavily, for the despair of the blogger).

There is simple explanation for this fact, though. Feedburner delivers your feed to a myriad of RSS readers. There are basically two types of RSS readers: web-based readers like Bloglines or MyYahoo and on-demand readers like FireFox Live Bookmarks. The web-based readers will pull your feed whether the subscriber opens his reader page or not, hence why the feed count for web-based readers is stable over the time. On-demand readers, however, will only be counted if the user actually accesses the feed on a particular day.

Here is a quote from Eric Olson, responsible of the Publisher Services for Feedburner:

We can only track the subscriber we see in a given day. If someone doesn’t open their feedreader or live bookmarks than we can’t count them that day and won’t count them on your stats.