A judge this week granted class-action status to antitrust litigation that now covers 21 million Google Play customers in 12 states—Alabama, Georgia, Hawaii, Illinois, Kansas, Maine, Michigan, Ohio, Pennsylvania, South Carolina, Wisconsin, and Wyoming—and five US territories, including American Samoa, Guam, Northern Mariana Islands, Puerto Rico, and the US Virgin Islands.“In effect, Google demands that each class member individually prove an injury before certification may be granted,” Donato wrote in his order.Experts clash over Google Play price modelsTo help the judge decide if the lawsuit is best settled with individual plaintiffs or as a class action, both sides provided expert testimony.Google argued in part that Singer used methods to calculate prices in the Google Play Store that Google’s expert, Michelle M. Burtis, had “never seen before.”According to Google, another alleged flaw in Singer's analysis was that Singer failed to account for real-world data impacting how developers make decisions to raise or lower prices based on app store fees.Burtis claimed that Singer’s analysis predicted that all developers would have lowered prices if Google Play lowered its fees, but Burtis’ analysis of how developers actually responded when fees were lowered showed that “only a tiny fraction of developers whose service fees Google reduced then reduced prices.”Ultimately, Donato denied Google’s motion to exclude Singer’s testimony, writing in his order that Google’s argument against Singer’s methodology “is the stuff of cross-examination and not exclusion.” Further, Donato said, “it is not necessarily ‘surprising’ for expert opinions to be based on methods that are new and not been the subject of peer review.”Neither Burtis nor Singer responded to Ars’ requests for comment."