If a given state releases most inmates at half their maximum sentence, then a judge will impose a ten-year sentence if he or she thinks the inmate should serve five years. There is nothing deceptive about this. In fact, parole has long been recognized as the most important positive reward that prison wardens can hold out for good behavior. While human judgement is not infallible, these officials are using the information and resources at hand to attempt to provide justice and contribute to community safety. Responsible officials and policymakers understand that criminal justice policy should be based on accurate data and analysis.
Ideologues are more easily satisfied with misrepresentative displays of admittedly complex data.
Unfortunately, the Council on Crime in America has published a report that will serve the interests of ideologues more than it will policymakers. The same study also found that increasing the time served in prison by offenders did not generally lead to reductions in recidivism.