To sum up: You have the dubious concept of “microaggression,” which was concocted a decade or so ago. You then had students read articles and look for “microaggressions.”
No sophisticated stats here. All you did was count phrases that you or your students subjectively felt were microaggressions.
Apparently. your hypothesis was that there would be more (flexibly defined) “microaggressions” in a later year than in an earlier year(s).
So, assuming that the difference is not an artifact of your counting procedures, so what?
You are apparently trying to prove that the media is becoming more sexist, or something.
But “microaggression” is so fuzzily defined that the results are, to say the least, subject to dispute.
Example: Any observer of women’s tennis will note that the Williams sisters are physically overpowering players, more so than any of their opponents. But, at least per the ThinkProg article, such an observation is a “microaggression.”