It was fairly widely reported (including by Venture Beat - though they didn’t quote any of NetRatings’s numbers, why not?) that Facebook unique visitors dropped 9.3% from August to September 2007 [Facebook profile]. We took a closer look at the demographic changes from August to September 2007 with respect to Facebook’s US traffic figures, as reported by comscore Media Metrix. Setting aside the interesting point that the majority (19.4mm out of 30mm UVs reported by Media Metrix) have as “Head of Household Education” the value of “Unknown”, the demographic splits aren’t super surprising. The drop does seem less of a problem related to methodology (though yes, those are ongoing issues to be examined for all the data vendors) and more of a seasonal “back to school” delta.

Here is a PDF with the comparison: Facebook demographic information comparison

There are notable drops in persons from ages 6-17 (14-16% vs. the 9.3% overall drop), and interestingly enough, from ages 35-44 (drop index at 185, or 17.2%). Could it be that parents are also dropping off from watching what their teenage kids are doing on Facebook? Females age 35+ saw a higher than average dropoff (155 index) and again, doing the headsup comparison in female 35-44 vs. male 35-44 we see a 212 index drop on the female side compared to a decent-sized but smaller 151 index drop on the male side. If we assume that women are more likely to be watching the kids’ activities, this could partially explain some of the seasonality detail. Older women in general had some larger drops with 35-49, 35-54 and 35-64 groups according to Media Metrix all seeing falls of over 150 index.

Note here we’ve indexed 100 to be 9.3%, the average drop overall in the traffic figures. The large drops in the HOH Education demographics don’t move us very much since most of that demographic is classified as “unknown” by comscore.

With such a rapidly-growing site, we don’t think it’s worth examining the year-over-year numbers at this stage, but we eagerly await next month’s figures to put things into perspective.