It’s very hard to record crime rates in prisons. Incarcerating people likely to commit crimes will mean their future crimes are much less likely to be reported

It’s very hard to record crime rates in prisons. Incarcerating people likely to commit crimes will mean their future crimes are much less likely to be reported. This does not mean less crime, it means crime just isn’t being recorded. Even the most rigorous studies account for crimes committed in prisons.