Supplementary Text

Validation of gender inference. We first validated the genderize.io algorithm using a set of 3265 names whose gender had been hand-coded based on appearance (1). The names were supplied to the genderize algorithm both with and without the accompanying country data. The genderize algorithm returned gender inferences for 2899 queries when first names were given and 2167 when country data was also supplied (732 names were associated with countries unsupported by genderize).