The constant multiplier assumption misestimates long-term sex offender recidivism rates.

Many clinical psychologists have claimed that long-term sexual recidivism rates are a fixed multiple of short-term rates and have estimated that the true value of this constant falls somewhere between 1.5 and 3.0.

Sampling Extreme Groups Invalidates Research on the Paraphilias: Implications for DSM-5 and Sex Offender Risk Assessments.

Psychiatrist and Diagnostic and Statistical Manual of Mental Disorders, 4th edition (DSM-IV) text editor Michael First has criticized the addition of victim counts to criteria proposed by the Paraphilia Sub-Workgroup for inclusion in DSM-5 because they will increase false-positive diagnoses. Psychologist and Chair of the DSM-5 Paraphilia Sub-Workgroup, Ray Blanchard, responded by publishing a study of pedohebephiles and teleiophiles which seemed to show that victim counts could accurately identify pedohebephiles who were selected per self-report and phallometric testing. His analysis was flawed because it did not conform to conventional clinical practice and because he sampled groups at opposite ends of the clinical spectrum.

Recent research (N = 9,305) underscores the importance of using age-stratified actuarial tables in sex offender risk assessments.

A useful understanding of the relationship between age, actuarial scores, and sexual recidivism can be obtained by comparing the entries in equivalent cells from "age-stratified" actuarial tables. This article reports the compilation of the first multisample age-stratified table of sexual recidivism rates, referred to as the "multisample age-stratified table of sexual recidivism rates (MATS-1)," from recent research on Static-99 and another actuarial known as the Automated Sexual Recidivism Scale. The MATS-1 validates the "age invariance effect" that the risk of sexual recidivism declines with advancing age and shows that age-restricted tables underestimate risk for younger offenders and overestimate risk for older offenders.