Study claims Explorer is leading

The latest study to measure who is winning the Internet browser wars estimates that Microsoft (MSFT) has made handsome gains in the last four months, boosting its "usage" market share from 42 percent to more than 63 percent.

The methodology used in the study remained unclear, however, and Microsoft's rival, Netscape Communications, predictably did not find the study credible.

According to a statement issued by Positive Support Review, Microsoft's Internet Explorer browser was used in 63.3 percent of the 550,000 Internet sessions studied. By contrast, Netscape's Navigator was used in only 35.6 percent of the visits measured, the release said.

It was unknown exactly how PSR made its estimates, and the numbers contradict a number of other studies. One study, which was conducted by research group Dataquest and cited recently by Microsoft, estimated that Netscape still held the lead with 57 percent, compared to Microsoft's 40 percent.

Microsoft spokeswoman Pam Kahl said she would not be surprised by a report that found higher numbers. "Microsoft has worked hard to establish strong partnerships," she said, adding that IE has been roundly praised in product reviews.

But Maggie Young, a spokeswoman at Netscape, questioned the study's findings. "We don't find this to be credible," Young said. Recently, Netscape released figures that showed Navigator with a 67 percent share of the market.

The issue of how to measure browser market share has remained contentious, and studies tend to present widely diverging estimates. Representatives from PRS were not available to discuss the study.