WebSideStory is trying to cause a stir by claiming that adoption of Firefox is slowing down. They show that relative increase of Firefox usage was lower between January and February than between November and December. While this is true, it’s rather misleading. For the relative growth rate to be constant Firefox would need to increase exponentially. The Firefox downloads are increasing in a close to linear fashion. Stats Weenie has some calculations showing that the real decrease in adoption is much lower.
The OneStat browser report is confused as usual. This time they mix up Mozilla browsers in general with Mozilla Firefox, as well as using both commas and dots as decimal separators. They also split the browsers up differently than in their previous browser press relase, making comparisons difficult or impossible.
Update: I sent an e-mail to Erik Bratt at WebSideStory this morning, and just recieved a reply stating that they are planning to change the wording of the report.
Update 2: WebSideStory have now changed the numbers. In reality, the Firefox adoption rate has not decreased significantly since the beginning of December. Between 2004-12-03 and 2005-01-14 the average was 0.0212 percentage points per day, and between 2005-01-03 and 2005-02-18 it was 0.0211.