A new study reviewing 75 group-randomized cancer trials over a five-year stretch shows that fewer than half of those studies used appropriate statistical methods to analyze the results. The review suggests that some trials may have reported that interventions to prevent disease or reduce cancer risks were effective when in fact they might not have been. More than a third of the trials contained statistical analyses that the reviewers considered inappropriate to assess the effects of an intervention being studied. And 88 percent of those studies reported statistically significant intervention effects that, because of analysis flaws, could be misleading to scientists and policymakers, the review authors say.