The only indisputable effect of imprisonment is that it prevents preying upon the general public for the duration. Since criminal behavior markedly decreases with age, there is a rational argument to be made that persons who prey on others should be removed from society until such time as they are old enough to knock it off.
Unless prison radializes them and conditions them to integrate even less with society. Then it would have the opposite effect you desire, even if statistics painted the picture you want to see.
