If I understand correctly, the author's relied on common 1st names from the UＳcensus for identifying

I' d like to invite you to address a third issue, that is, the lack of 

To determine the extent to which such an approach may lead to the inclusion of abstracts written by L2 authors in the MIT corpus, we randomly selected 100 abstracts from the MIT corpus and attempted to verify the L1 status of the 100 authors case by case using as much information as we could find about them online. Two of the files contained bio-sketches with hometown or home country information, and all files form the Department of Chemistry contained a CV. We 

In light of this new finding, the following footnote was added