Is this accurate, and/or backed up by research?
I have no idea myself, but seen that it's been mentioned a lot. I can maybe see it happening in male prisons, by virtue of there are more male prisoners, gang culture, more violent crimes are committed by males and things of that nature. But female prisons tend to be less populated (less chance of this happening and more in the eye of prison staff), and the exhibition of better behaviour by prisoners, and generally, they're non violent prisoners and possibly less lengthy sentences.
Like I said, I have no idea, but would be interested to know if that is backed up by any research.