Feedburner issue: Is the Firefox subscriber count inflated?
January 9th, 2007 by Stefan JuhlAre you using Feedburner for feed stats? If you do and if you’re almost jumping up to dance on your desk in happiness of your many subscribers - then don’t read on unless you’re ready to become disappointed! The truth is that Feedburner’s ‘Firefox Live Bookmark’ subscriber count seems very inflated.
A couple of days ago Markus from AU interactive wrote a in blog post that 75% of his blogs feed reader audience uses Firefox Live Bookmarks. He then goes on to conclude that it’s because of when a feed is shown Firefox then Live Bookmarks is the default feed subscription method. I do think that Markus is somewhat correct in his assumptions on ‘the power of the default’ getting a lot of people to use Live Bookmarks for feeds. The problem is that his Feedburner stats is probably way of.
Firefox is requesting/prefetching a feed if it’s just correctly listed in the HTML head of a requested page. So it means that whenever someone visits your blog through a Firefox browser they’ll also request your RSS feed. Feedburner seems to counts a lot of the unique users’ requests of feeds which leads your Feedburner stats for ‘Firefox Live Bookmarks’ to be somewhat inflated.
I’m not sure if this applies to all Firefox versions but at least it is so for the newer versions. A good way to check this is by installing the Live HTTP headers plugin and watch the request being performed when you visit a blog or website. One thing I noticed is that sometimes Firefox does send the header ‘X-Moz: prefetch’ but it’s seems to be far from every time that the prefetch header gets sent.
And if you want to see the request being counted be Feedburner, just set up a new feed in feedburner, list the feed in the html head of a “secret” page, and visit that page once without ever visiting or subscribing to the feed. Then tomorrow you’ll see that the feeds says you’ve got 1 Firefox Live Bookmark subscriber - which is not correct..!
Considering the major spikes appearing in Feedburners graphs after a day with heavy traffic (see image) and Feedburner stats stating it to be Firefox subscribers. And the fact that most of the counted Firefox Live Bookmarks subscribers is gone the next day according to the graphs, then I can only assume that it is definitely a real issue.
The big question is who to blame… Firefox, Feedburner or shouldn’t we blame anyone..?
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Posted in Random Stuff, Blogging |
January 9th, 2007 at 3:06 pm
I’d have to with Feedburner to blame on this one.. It’s their product, it’s their responsibility to know these issues, contact the mozilla team and figure out a way around this..
January 9th, 2007 at 4:22 pm
Stefan -
Really appreciate you raising this issue. I hadn’t heard that Firefox was prefetching feeds on page loads - I’ll get our dev guys to reproduce that behavior internally, and assuming that it’s news to them, we’ll absolutely adjust our measurement of Firefox accordingly. Thanks for catching this!
You raise a somewhat unrelated issue, which is the situation in which a feed receives an unusual amount of views in a 24 hour cycle. Since Firefox doesn’t distinguish itself when it accesses feeds (both the browser and LiveBookmarks advertise themselves as Firefox), we have to do our best to guess whether the particular access we’re seeing is an automated access (i.e., a feed request from LiveBookmarks, in which case they should be counted as a subscriber) or a manual one (in which case it’s the browser, and it’s someone viewing the feed without necessarily subscribing to it - and we wouldn’t count them in the subscriber number). Inevitably, we’ll get some calls wrong - though the evidence would suggest it’s an automated request (i.e., it’s in a time interval that suggests periodic retrieval), it’s in fact coincidental and it’s just someone viewing it in the browser.
Other browsers like IE7 *do* distinguish themselves depending on the context in which they’re accessing the feed, so it’s less likely that there will be as much inferences to draw about whether we’re seeing a subscriber or not.
Hope this helps - and I’ll follow-up on the prefetch issue and let you know what (if anything) we do to our algorithms as a result.
Regards,
Rick Klau
VP, Publisher Services
FeedBurner
January 9th, 2007 at 5:15 pm
Hey Rick, thanks for responding here!
Maybe this is relevant. I tested with Firefox version 2.0.0.1 and 1.5.0.9. Also, it seems that whenever the feed is redirected with a 302 (I haven’t tested others like 301, 307 etc.) Firefox don’t send the X-moz: prefetch header. Which I’d mean it should do..
The thing about a heavy traffic increase was mainly to “illustrate” what it looks like. And it was that which brought it to my attention.
January 9th, 2007 at 5:33 pm
Stefan,
It is probably a Feedburner issue. Overall, I’m glad they provide the service. I’ve been told subscribers are more inclined to read and forward the email feeds then try to reference the content of my blogs (it’s easier for them). Thanks for the post, nice site btw.
PS: Thanks for stopping by and visiting me on MyBlogLog - another service I enjoy using.
January 10th, 2007 at 12:49 am
Mozilla shouldn’t be prefetching anything other than rel=next and rel=prefetch (and I’m not seeing it fetch feeds), please file a bug if you can reproduce the issue on a clean setup (without extensions, etc.).
Rick, Firefox 2.0.0.1 has exactly the feature you describe, and according to bug 356463, FeedBurner requested it.
It’s “X-Moz: livebookmarks”.
January 10th, 2007 at 2:48 am
hi,
I’ve (maybe) the same problem with netvibes…
Here is the topic in the support forum.
http://forums.feedburner.com/viewtopic.php?t=10200&highlight=netvibes
January 10th, 2007 at 3:18 am
Thanks for pointing this out! Nice investigative work. Glad to see Rick comment as well.
January 10th, 2007 at 5:01 pm
[…] Update: Check out Stefan’s post about how Firefox handles subscriber counts and how the stats above might be wildly inaccurate because of it. […]
January 10th, 2007 at 11:59 pm
Robert (comment 5) - yep, confirmed with our dev team that we are aware of it (and did request it!). We hadn’t been able to distinguish cases where we *did* see the prefetch header and where we didn’t, and it looks like Stefan has caught that in the wild which is a big help. We’re doing some investigating on this side, and will post an update once we have anything newsworthy to report.
Thanks to everyone for the input.
–Rick
January 12th, 2007 at 5:08 pm
[…] Stephan Juhl wrote a post a few days ago claiming that Firefox’s “live bookmarks” feature might be artificially increasing the subscriber count in FeedBurners stats: A couple of days ago Markus from AU interactive wrote a in blog post that 75% of his blogs feed reader audience uses Firefox Live Bookmarks. He then goes on to conclude that it’s because of when a feed is shown Firefox then Live Bookmarks is the default feed subscription method. I do think that Markus is somewhat correct in his assumptions on ‘the power of the default’ getting a lot of people to use Live Bookmarks for feeds. The problem is that his Feedburner stats is probably way of. […]
January 14th, 2007 at 1:24 am
Congrats for this beautiful article.
I just based an article on your, reccomending wordpress users with FF subscribers count inflated to use the Fedafi Plugin for feed stats.
Matteo L. Turchetto
January 14th, 2007 at 10:58 am
Rick, yeah it was kind of a coincidence that I noticed the prefetch header was missing after a 302 redirect. I hadn’t found any cause for when I saw it or not, before after having published this.
Matteo, I don’t know the Fedafi plugin but it will most likely have some of the same issues. Have you checked how it handles and reports on prefetches and if it is using redirects etc. and then making the prefetch headers disappear?
January 15th, 2007 at 12:18 am
Thanks for Tip. I’ll check it ASAP
January 15th, 2007 at 5:16 pm
Check out what it says for rojo now. I had 3 feeds that went from 80+ subscribers to less than 10 overnight.
“Due to a bug with the way Rojo is reporting subscribers for some feeds, we’re temporarily disabling the Rojo count in subscriber numbers. Rojo is aware of the issue and is working on it. Once the fix is in place and the numbers are accurate, we will resume including Rojo’s subscriber count here.”
January 31st, 2007 at 2:25 am
Great analysis! Your subscriber base has just “inflated” by one.