This revision addresses community feedback, specifically and most substantially:

(1) controlling covariates using propensity score matching,

(2) providing an interpretation of whether the differences are meaningful,

(3) including raw data used in figures as part of the appendix,

(4) characterizing the authors' own biases,

(5) adding section examining "Are women focusing their efforts on fewer projects?",

(6) comparing GitHub developers that are on Google+ to those who are not,

(7) adding analysis of exclusively projects that are licensed as open source,

(8) addition of statistical tests and corrections for false discovery, as appropriate,

(9) replacing bar chart representation of pull request acceptance rate,

(10) characterized missing data, and

(11) adding threats of uncaptured covariates and developer aliases.

The paper has a slightly revised title (adding "differences and") and we have added an author, Jon Stallings, who has contributed substantially to the revision.

Additionally, we have revised our data analysis pipeline substantially to use R scripts that extract data from our database and produce latex macros that define numerical results. We believe this improves the reliability of our analysis. In doing so, we found and fixed errors the following errors in the prior version:

* Y-axis in Figure 2 was previously truncated and means and medians in caption were incorrect,

* Rounding errors and transposition of "files changed" and "commits" in "Are women making smaller changes?",

* Incorrect summation of "without reference" pull requests, and consequently the accompanying percentages, in "Are women making pull requests that are more needed?", and

* One programming language difference (.m) was previously incorrectly reported as statistically significant.