In the first three months, long-distance relationships are no more likely to break up than those where the couple live close to each other, according to a 2005 study of 162 college students at Central Michigan University. That’s a kind of important finding given that as many as 75 percent of American students report having a long-distance relationship (LDR) at some point during college.

But three months isn’t very long, and 162 college students isn’t very many, right? To get a bigger study, I needed to look a lot further afield — to a dissertation written in Germany in 2010. After putting out a nationwide news release, Fanny V. Jimenez, then a fellow at Humboldt University of Berlin, found 971 participants in long-distance relationships and 278 participants in proximate relationships (PRs). Jimenez found that for LDRs, the average relationship length was 2.9 years (the standard deviation — one way to measure how much variance there is in the data — was 3.2 years). For PRs, the average relationship was more than twice as long, 7.3 years (the standard deviation was larger, too, though, at 7.5 years).

Which doesn’t sound like good news for couples who are long-distance and want to stay together. Except that those averages are pretty basic. They don’t factor in things like age or marital status, which could have a big effect on the average length of a relationship.