^ Um, no. Freshman retention for 2019 is specifically defined as “Percentage of Students Who Began Their Studies in Fall 2018 and Returned in Fall 2019.” That’s not dropping out sophomore year. But you are correct that it DOES include anyone who doesn’t complete freshman year as well as those who do. However Harvard wishes to describe it, the proportion who don’t come back is 3%. (I guess it’s very hard to “drop out” if the university doesn’t acknowledge that you’ve done so LOL). My guess is that some of them actually do transfer to another institution and H doesn’t report that. They aren’t obligated to for IPEDS.
In contrast, UChicago actually expects your leave of absence not to exceed eight quarters and will usually withdraw you after that point.