> ....in a ratio that differs from the expected gender distribution for the job.
It would be interesting to see the expected gender distribution stats for the jobs in question in addition to the difference shown by Facebook so we have something to compare to.
Regardless of how discriminatory Facebook's job ad serving is, I would have expected it to track engagement by preference, which LinkedIn possible does not.
It would also be interesting to see how well engagement correlates to interest in the job, which you would have expected to be an important metric: you don't want to serve ads to people that are not interested. The suggestion of the research is that it does not or is not sufficiently aligned, but unless we can compare the two sets of figures, then it is difficult to form an opinion.