According to C. N. Parkinson (earlier discussed here), socioeconomic classes are recycled by a tendency for the top of the ladder to adopt downwardly-mobile habits and the bottom of the ladder to adopt upwardly-mobile habits.
The women from less-privileged backgrounds were the upwardly-mobile and those from more-privileged backgrounds were the downwardly-mobile. I suspect the most chaste women were those that transferred out of the party school to a real university and were lost to the study.
About two-thirds of the students came from what they called “more privileged” backgrounds, meaning they had financial support from their parents, who were probably college-educated themselves. A third came from less privileged families; they supported themselves and were probably the first in their family to go to college.
The most revealing parts of the study emerge from the interviews with the less privileged women. They came to college mostly with boyfriends back home and the expectation of living a life similar to their parents’, piloting toward an early marriage.
In related news, the lowest abortion ratios in New York City (as of 2009) could be found in zip code 10282, otherwise known as the “1 percent.” (It edged out the Orthodox Jewish district 11219 by a statistically-insignificant amount.)