The first lesson he learned is that a lot of programs based on various theories of modifying offenders' behaviors and attitudes don't work in achieving the purpose of corrections, i.e, preventing reoffending (recidivism) over time. The second lesson he learned is that if reducing recidivism is the goal of a program, it is important to focus on those offenders who are most likely to reoffend. These high-risk offenders should receive the most intensive treatment for a longer period of time compared to low-risk offenders. Studies have shown that providing low-risk offenders with the same intensity and dosage of programming as that received by high-risk offenders can increase reoffending by low-risk offenders. Identifying high-risk and low-risk offenders is dependent on showing what factors in various combinations increase or decrease the risk for reoffending for various types of offenses. This requires in-depth and extensive research on factors that alone and/or in combination with other factors increase the risk for particular criminal behaviors. Another lesson mentioned in the presentation is that the certainty and severity of punishment may deter low-risk offenders from reoffending, but generally they have little effect on high-risk offenders, who require that the risk factors that have molded their behavior must be addressed.