Does gender diversity in the boardroom improve company performance? This question has been comprehensively researched and debated for many years, however definitive evidence has remained elusive—until now, perhaps. A comprehensive research report just published by Credit Suisse shows that companies with gender diversity in the boardroom perform better than companies with all-male boards, using data from 2360 companies from 2005–2011.

While the results show some definite trends (the benefits of diversity within management, for example), the researchers stopped short of attributing the increased performance to the presence of women on boards. Clearly, diversity is having an impact, but how and why? As the report states, "there is not one easy answer to why gender diversity matters". Could it be that a wider set of experiences and viewpoints is contributing to a more vigorous debate; or that the presence of women leads to a greater level of engagement by board members? The results from the Credit Suisse report are helpful, but the bottom line is that we simply don't know—yet.