On the agenda of yesterdays ABCE ITG meeting was the discussion of an RSS referral meteric, referring to a link clicked from an RSS feed. The problem was sounded that a number of RSS readers will pre load a page, or render a page to get a screen shot when you view a feed, leading to over counting. Another member of the ITG also brought up that often unique RSS links were posted on blogs, shared over Netvibes or other news aggregators such as Google News, causing huge peeks in traffic.
However it transpired that these variations would be shared equally between sites, just as the effects of web accelerators are, and particular spikes in traffic could be easily identified.
The conversation then turned to the metric for an RSS subscriber. Essentially this would be a user subscribing to an RSS feed. The problem is, the more you analyse it the more you realise how hard it is to measure.
Ideally you would check the unique users that request the feed. However the nature of RSS not being pushed to users, means readers will request a feed to check for updated numerous times over a day. These RSS aggregators may only be run on some days (weekends only perhaps). Then one of the largest problems is that the aggregators vary dramatically, some are applications similar to web browsers, others are online applications like Google reader, some use simple CURL, some may proxy the result for larger networks, or be feeds of feeds (Sharing in Google Reader for example). The chances of all the readers accepting cookies is slim, but also the IP is likely to change, or even be shared for millions of people (again Google reader or Google news).
This all leads to the question, how can you count and audit it? Well FeedBurner seems to be able to, so the question is, how do they do it? Well FeedBurner was recently purchased by Google, meaning Google probably had the same questions we have...
Looking deeper into FeedBurner you notice they are very transparent and also vague over the term subscribers, splattering "on average" everywhere. Their definition of a Subscriber is:
Subscribers is an approximate measure of the number of individuals currently subscribed to your feed.
More information on Subscriber explained.
So it looks like even the powers at Google can't really figure it out, but at the end of the day, should we even be doing this. The whole point of RSS is that it's an anonymous form of subscription, you don't have to give any information out! If you did then wouldn't we still just be using Email subscriptions?
Perhaps the only way to really do it, is to have a unique feed URL generated every time someone visits a page. A bit of an overkill granted, and even then there are still more holes in the suggestion than your average block of Swiss cheese!
So lets stick to the vague guessing, and I hope my 8,352 subscribers enjoy this post ;)