Among the other DGA winners were Searching for Sugar Man director Malik Bendjelloul, who won the guild's documentary award for his study of the obscure singer-songwriter Sixto Rodriquez.
There are more women working in documentary films than narrative films, but study director Stacy Smith said her research found that "as commerce moves in, females move out".
The ongoing study is like the science-y version of the "7-Up" documentary series -- with researchers checking in on the lives of the subjects at several-year intervals.