You can get a complementary analysis by comparing the US to its past self. Incarceration rate, homicide rate. Between 1975 and 2000, the incarceration rate grew five-fold while the homicide rate fell by half.
That analysis doesn’t tell you whether growing the incarceration rate was necessary to deal with the high homicide rate and get it to fall in half.
You could get that by comparing with other countries that reduced their homicide rates by similar amounts over similar timescales.
You can get a complementary analysis by comparing the US to its past self. Incarceration rate, homicide rate. Between 1975 and 2000, the incarceration rate grew five-fold while the homicide rate fell by half.
That analysis doesn’t tell you whether growing the incarceration rate was necessary to deal with the high homicide rate and get it to fall in half.
You could get that by comparing with other countries that reduced their homicide rates by similar amounts over similar timescales.