Nielsen, Compete Show Normal US Traffic Gains for Facebook in May 2010

Did May’s very public backlash against Facebook’s April privacy changes and product launches actually affect traffic? The web measurement results are coming in now. ComScore was the first web measurement firm to weigh in, and it showed that Facebook gained 8.6 million monthly unique visitors to reach around 130 million.

Two other firms, Nielsen and Compete, have now released their own data for the month, and they both show slower Facebook May growth than Comscore. Triangulated, however, they and comScore show three contradictory trends. Here’s the data; note that we’ll do a full look later this month, once the fourth firm we track, Quantcast, makes its May data available.

Nielsen shows Facebook growing by 2.91 million, from 122.3 million uniques in April to 125.2 million, in the US. This is slower than the 5 million that Nielsen showed Facebook gaining in April, but around the same as what it gained in February, and much more than the 2 million it lost in March. In this context, May’s traffic was pretty good for Facebook.

ComScore, meanwhile, shows a dip in February but a solid rise starting in March, as we recently covered.

Compete‘s data for May adds a new twist. It has Facebook gaining 2.1 million users, from 121.7 million uniques in April to 123.8 last month — from there, the similarities with Nielsen’s data end. It shows Facebook’s traffic rising and falling during 2010, starting with 121.2 million in January, and this is not what the other firms show.

But that’s not the only twist — Compete seems to have chopped off 10 million or so users that it had previously counted for Facebook. As of April, for example, it showed 135 million uniques, and in March it showed 132 million.

Ignoring methodology-based differences between these firms, the trend is that May was a good but not exceptional growth month for Facebook.