The Research:

“Professors Woolley and Malone, along with Christopher Chabris, Sandy Pentland, and Nada Hashmi, gave subjects aged 18 to 60 standard intelligence tests and assigned them randomly to teams. Each team was asked to complete several tasks—including brainstorming, decision making, and visual puzzles—and to solve one complex problem. Teams were given intelligence scores based on their performance. Though the teams that had members with higher IQs didn’t earn much higher scores, those that had more women did.”

Read more about this research here: http://hbr.org/2011/06/defend-your-research-what-makes-a-team-smarter-more-women/ar/1