The online encyclopaedia invites anyone to edit entries
Wikipedia has disputed claims that it has lost a huge number of editors that help maintain the online encyclopaedia.
On 26 November it was reported that ten times more editors had left Wikipedia in early 2009 than during the same period in 2008.
The group overseeing the reference work said the claims on losses were not accurate, blaming a difference in what counts as an "editor".
By contrast, it said, the numbers of people editing Wikipedia were stable.
In a blog post the Wikimedia Foundation responded to the publication of a report by researcher Dr Felipe Ortega which said that 49,000 editors had departed Wikipedia in the first three months of 2009.
Dr Ortega's comparisons suggest that only about 4,900 left the site in the first few months of 2008.
Wikipedia relies on editors to keep the online reference work up to date, expand entries and make corrections.
Writing on the blog, Erik Moeller, deputy director of the Wikimedia Foundation, and Erik Zachte, one of its data analysts, said that while Dr Ortega's article comprehensively described the challenges and opportunities facing Wikipedia it mischaracterised the changes in its editing population.
The pair said that the numbers of people contributing to Wikipedia hit a high in early 2007, declined slightly and have since stabilised.
"Every month, some people stop writing, and every month, they are replaced by new people," they wrote.
The confusion arose over the differing definitions of what constitutes an editor. Dr Ortega counted everyone who made one change as an editor giving a total population of three million people.
By contrast, the Wikimedia Foundation counts only people who make five edits or more as an editor. This gives an editing population of about one million people across all languages. Of that total, the English edition of Wikipedia has about 40,000 editors.
The pair also disputed Dr Ortega's attempt to measure when Wikipedia editors start and stop.
"It's impossible to make a determination that a person has left and will never edit again, there are methodological challenges with determining the long term trend of joining and leaving," read the blog.
The Wikimedia Foundation said it was continuing to work with Dr Ortega to iron out some of the methodological difficulties and uncover long term editing trends.