Even after accounting for unrelated variables, the researchers found that a 10 percent nominal increase in the percentage of female managers (at the level of the then-prevailing glass ceiling) was associated with a 1 percent nominal increase in ROA.
"The results are pretty strong that even when you control for anything that's fixed about a company, it appears that increasing your female managers leads to higher profitability over time," says Siegel.
via hbswk.hbs.edu