The Michigan Department of Correction developed parole guidelines in 1984 to “reduce the potential for disparity in parole decisions and to explicitly define the bases upon which rational and equitable parole release decisions should be made,” according to an MDOC report. That is, they were initially conceived to make decisions more objective and consistent, not to statistically assess risk.
The ability of the instrument, as a whole, to predict an individual’s risk of re-offending was validated in 1992, 1993 and 2001. However, the predictive value of each individual factor scored in the guidelines has not been established. That is, the instrument as a whole successfully separates prospective parolees into categories based on their likelihood of committing either an assaultive felony or any felony at all, but the actual impact of most specific factors is unclear.