For Incoming I.B.M. Chief, Self-Confidence is Rewarded

Interesting NYTimes article about the new CEO of IBM, Virginia Rometty. I was curious about the suggestion the reporter made as a possible explanation for the barriers women still face in attaining C-suite positions within the tech industry:

"Companies have trouble retaining technical women because they are often isolated from influential social networks inside companies, Ms. Simard said. "

I wonder if she or someone else has done an SNA documenting this.