Misquoting and Misapplying Prentky Statistics
THE CLAIM: Many folks claim that after 25 years sex offenders' recidivism is 52% for child molesters and 39% for rapists, and they cite Prentky 1997.
THE PROBLEM: Many folks are misquoting and misapplying R.A. Prentky's 1997 long term recidivism study and its findings to ALL sex offenders when those recidivism rates should ONLY apply to folks released from Massachusetts' civil commitment center back when Prentky was Director of that civil commitment center.
THE CAUSE: Whn folks cite stats they fail to recognize who Prentky is [was], and who his study subjects were, and are unaware of the Prentky's caution about misapplying the study findings. Prentky himself failed to carry forward his own caution from one study to his next study, which affected and may have inadvertently mislead the US Supreme court in
Smith et al. v. Doe et al. 538 U.S. 84 (2003). The main sex offender case cited even today.
Who is R.A. Prentky? Dr. Prentky was Chief Psychologist and Director of Research at the Massachusetts Treatment Center for Sexually Dangerous Persons (MTC) from 1980 until 1993. (pg-45 footnote 45) ... In July, 1997, Dr. Prentky returned to the Massachusetts Treatment Center as Director of Assessment. MTC is the state's civil commitment center. All of Prentky's study subjects are persons who had already committed many sex offenses causing their commitment to MTC, and then were released. Prentky published four studies in 1997 based on MTC subjects.
(see below Prentky's 1997 Studies-A, B, C, and D).
(C and D is where the confusion occurred)
POINT-1: Confusion Caused by Study-C and Study-D:Accordingly, anyone who reads Study-C will never know they SHOULD NOT apply its findings to anyone but sex offenders released from civil commitment centers. This has caused many to misquote the study and its statistics. See below for a shock as to who has misquoted these two studies.
When Prentky published Study-C he had just finished Study-D, but it was not yet published. See his comment in Study-C [excerpt p-11] where, in footnote 28, Prentky mentions Study-D.
POINT-2: Study-D Prentky Caution Missing from Study-C:
Now, notice Prentky's closing WARNING about the findings of Study-D: "We would like to conclude with two important caveats. The obvious, marked heterogeneity of sexual offenders precludes automatic generalization of the rates reported here to other samples." This comment was not included in Footnote 28 of Study-C.
US Supreme court in Smith et al. v. Doe et al. 538 U.S. 84 (2003): The court's opinion cited Study-C which is missing Prentky's WARNING:
"Empirical research on child molesters, for instance, has shown that, "[c]ontrary to conventional wisdom, most reoffenses do not occur within the first several years after release," but may occur "as late as 20 years following release." National Institute of Justice, R. Prentky, R. Knight, & A. Lee, U. S. Dept. of Justice, Child Sexual Molestation: Research Issues 14 (1997)."Accordingly, the court, while speaking of ALL sex offenders in society, incorrectly applied recidivism statistics which Prentky's WARNING (only found in Study-D) said not to do!
In the Smith case, according to the court's docket, several amicus curiae briefs were filed for the court to consider. Now, while I could not find all of those briefs I did find two that are relevant: Brief filed by the US Solicitor Generals office and one by The State of California, Attorney Generals office (for Attorney Generals of 43 other states), links below.
Those two briefs represent the findings, after review of the evidence and studies quoted, of over 40 lawyers. They quote from Study-D which contains the Prentky WARNING: "We would like to conclude with two important caveats. The obvious, marked heterogeneity of sexual offenders precludes automatic generalization of the rates reported here to other samples.It is shocking that so many would ignore Prentky's WARNING and infer that those statistics represent what ALL sex offenders in society are like. Remember, Prentky's words, WARNING that his statistics are not applicable to the overall class of sex offenders!
In closing, note the "Recidivism Comments During Oral Arguments" below. Now, everyone has the facts and should know, when and how, to apply the Prentky 1997 studies, and most importantly, when not to apply them!
Prentky Studies Published in 1997
STUDY-A)..Prentky, R. A., Knight, R. A., & Lee, A. F. S. (1997 Feb). Risk factors associated with recidivism among extrafamilial child molesters. Journal of Consulting and Clinical Psychology, 65, 141-149.
Title: Risk factors associated with recidivism among extrafamilial child molesters.
Abstract: This study examined the predictive efficacy of 10 rationally derived, archivally coded variables for assessing reoffense risk among extrafamilial child molesters. Follow-up data on 111 child molesters who were discharged from the Massachusetts Treatment Center between 1960 and 1984 were used. Degree of sexual preoccupation with children, paraphilias, and number of prior sexual offenses predicted sexual recidivism. Juvenile and adult antisocial behavior, paraphilias, and low amount of contact with children predicted nonsexual victim-involved and violent recidivism. Area under the receiver-operating characteristic curves in all three analyses indicated discrimination that was substantially better than chance, ranging from .73 to .79. (PsycINFO Database Record (c) 2006 APA, all rights reserved)
Source: Journal of Consulting and Clinical Psychology. 65(1), Feb 1997, 141-149. (Available from JCCP)
STUDY-B).. Prentky, R. A. (1997). Arousal reduction in sexual offenders: A review of anti-androgen interventions. Sexual Abuse: A Journal of Research and Treatment, 9, #3. Not relevant to recidivism issue.
STUDY-C).. Prentky, R. A., Knight, R. A., & Lee, A. F. S. (1997, June). Child sexual molestation: Research issues. Research Report, National Institute of Justice, Washington, D.C.
Title: Child sexual molestation: Research issues.
Executive Summary: Over the past 25 years, the problem of child sexual victimization has received significant attention from researchers, clinicians, and policymakers. Yet underreporting of sexual offenses against children has made it impossible to gauge either the frequency of such incidents or the size of victim and offender populations. In addition, deficient research methodologies have yielded incompatible or contradictory findings with regard to the characteristics, motivations, and recidivism rates of offenders. As a result, critical decisions about offender dangerousness, control, and treatment have been made in the absence of a sound knowledge base. In recent years, however, efforts have been made to (1) develop and validate an empirically based model of the agents and factors that lead to child sexual abuse, and (2) design and test statistical methods for assessing reoffense risk.
Source: National Institute of Justice, Washington, D.C. (Available from NIJ)excerpt p-11:
"To illustrate the variability in estimated recidivism, researchers used a data set on 251 repetitive sex offenders (136 rapists and 115 child molesters) released over a 25-year period from the Massachusetts Treatment Center (MTC) for Sexually Dangerous Persons. Only the data on child molesters are presented here. Using simple percentages and survival analysis, this information was examined from three measurement perspectives: 28"
Footnote 28: Prentky, R.A., A.F.S. Lee, R.A. Knight, and D. Cerce, Long-Term Comparison of Rate and Force of Recidivism Between Child Molesters and Rapists: A Methodological Analysis, 1996. Manuscript submitted for publication.
STUDY-D).. Prentky, R. A., Lee, A. F. S., Knight, R. A., & Cerce, D. (1997 Dec). Recidivism rates among child molesters and rapists: A methodological analysis. Law and Human Behavior, 21, 635-659.
Title: Recidivism rates among child molesters and rapists: A methodological analysis. (Full paper HERE)
Abstract: We address the high variability in sex offender recidivism rates by examining several of the critical methodological differences that underlie this variability. We used a dataset on 251 sex offenders (136 rapists and 115 child molesters) who were discharged over a 25-year period to examine changes in recidivism as a function of changes in dispositional definition of reoffense (e.g., arrest or conviction), changes in the domain of criminal offenses that are considered, and changes in the length of exposure time. The data indicate that: (a) both rapists and child molesters remain at risk to reoffend long after their discharge, in some cases 15-20 years after discharge; (b) there was a marked underestimation of recidivism when calculating a simple proportion (%) consisting of those who were known to have reoffended during the follow-up period, and (c) there was a marked underestimation of recidivism when the criterion was based on conviction or imprisonment. Forensic, clinical and policy implications of this high variability are discussed.
Source: Law and Human Behavior, 21, 635-659. (Available from ingentaConnect)
The participants in this study were 265 male sexual offenders who had been committed to the Massachusetts Treatment Center for Sexually Dangerous Persons (MTC) in Bridgewater, Massachusetts. The Center was established in 1959 under special legislation for the purpose of evaluating and treating individuals convicted of repetitive and/or aggressive sexual offenses. The legislation provides for a civil, day-to-life commitment by the court. Release is contingent on being found no longer "sexually dangerous."
We would like to conclude with two important caveats.
The obvious, marked heterogeneity of sexual offenders precludes automatic generalization of the rates reported here to other samples.
The crucial point to be gleaned from this study is the potential variability of the rates and not the sample-specific rates themselves. The actual rates may differ considerably depending on the composition of the sample (e.g., higher or lower proportion of exclusive incest offenders, higher or lower proportion of psychopaths, etc.).
The second caveat is that these findings should not be construed as evidence of the inefficacy of treatment. Although all of the men in our follow-up study were discharged from a prison treatment facility, the treatment services were not provided uniformly or systematically and did not conform to a state-of-the-art model.
RECIDIVISM Comments during Oral Arguments
MR. ROBERTS: -- Court has recognized, as recently as last June in the McKune case, for the conclusion that those convicted have a high rate of recidivism. ...
(excerpt from McCune: "When convicted sex offenders reenter society, they are much more likely than any other type of offender to be rearrested for a new rape or sexual assault. See id., at 27; U. S. Dept. of Justice, Bureau of Justice Statistics, Recidivism of Prisoners Released in 1983, p. 6 (1997) and others. States thus have a vital interest in rehabilitating convicted sex offenders.") That study has since been replaced by Recidivism of sex offenders released in 1994, published in 2003 [November 8 months after the March court decision] showing a very low recidivism rate.
QUESTION: May I ask you a question about that? I -- I understand that the -- the percentage of sex offenses in Alaska with children is extremely high, and what is -- has been the effect of this scheme if it's been employed? Has it had some effect there --
MR. OLSON: I --
QUESTION: -- in reducing the number of sex offenses?
MR. OLSON: I do not know the answer to that, and perhaps Mr. Roberts does.
But what this is -- and I think this is a proper way to think of this statute -- in connection with a class of offenses, where the -- where the rate of recidivism is significantly higher -- as this Court has held very recently -- than any other crime, people are asking their government please allow us to know when we have someone in our neighborhood. When we -- when we're hiring a new -- ....
QUESTION: I'm sorry. One -- one thing that makes it more difficult perhaps than it might be to see your side of the argument -- go back to the Chief Justice's question. What if they put every criminal conviction on the Internet?
Well, there's one difference between the situation that would obtain then and the situation that -- that you're objecting to here. That is, that there is not the same high recidivism rate for crimes generally that there is, apparently undisputedly, for sex crimes in the State of Alaska. And therefore, when you earlier made the argument that there is something very -- something less than credible in the State's claim that it's merely trying to inform the public when, in fact, it makes no differentiation between current dangerousness and un-current dangerousness, the answer is there is -- or an answer is -- there is a very high recidivism rate, and that high recidivism rate does support the claim that there is something that -- that it is credible to say that by publishing this information, we are simply trying to inform people of a probability of dangerousness, leaving them to do what they want.
What is -- is there any -- do you have any response to this claim that the high recidivism rate itself supports the argument that, in fact, this is nothing but a safety information kind of measure, whereas broadcasting all criminal convictions would not be justified as having a good fit between the object and what the State was doing? Do you have any response to that?
MR. THOMPSON: I certainly don't profess to be an expert on the statistical recidivist rates. I think that is --
QUESTION: You don't dispute the State's recidivism figure, do you?
MR. THOMPSON: Well, actually vis-a-vis the brief that was submitted by Massachusetts as an amici in this, sets forth a very different pattern of recidivist rates. I mean, when we say recidivist rates, are we talking about repeat sex offenses? Are we talking about repeated crimes? I mean, there are all different ways in which --
QUESTION: They're making specific -- they're making specific claims. They -- they set out specific percentages with respect to Alaska. Are you disputing those figures or not?
MR. THOMPSON: We do.
Chicago Tribune Article Ex: "Experts believe statistics present an incomplete picture of how many convicted sex offenders commit new sex crimes because only a fraction of sexual assaults are reported by the victims. Still, one study placed the rate of repeat offense within 25 years of conviction at 52 percent for child molesters and 39 percent for rapists." (Tribune reporting Lisa Madigan's comments, Illinois Attorney General, fails to cite any authority for their comment)
Datona Beach News Journal Online Article Ex: "But studies that have tracked sex offenders over longer periods have found that pedophiles who molest boys, and rapists of adult women were the types of offenders most likely to recidivate. Pedophiles of boys have a 52 percent recidivism rate and rapists of women have a 39 percent rate." (Fails to cite any authority for their comment)
The Center for Sex Offender Management (Part of the Dep't of Justice) Ex: "Conversely, Prentky, Lee, Knight, and Cerce (1997) found that over a 25-year period, child molesters had higher rates of reoffense than rapists. In this study, recidivism was operationalized as a failure rate and calculated as the proportion of individuals who were rearrested using survival analysis (which takes into account the amount of time each offender has been at risk in the community). Results show that over longer periods of time, child molesters have a higher failure rate—thus, a higher rate of rearrest—than rapists (52 percent versus 39 percent over 25 years)." (Discussion speaks about ALL sex offenders contrary to Prentky's WARNING, yet cites Study-D)
US Supreme court (Smith et al v. Doe et al, 2003, Sex Offender Registration): Brief filed by US Soliciter General's office Ex: Pg-4 Footnote: "R. Prentky, et al., Recidivism Rates Among Child Molesters and Rapists: A Methodological Analysis, 21 Law & Hum. Behav. 635, 642-643 (1997) (over 25 years, recidivism rate was 52% for child molesters and 39% for rapists)" Solicitor General (citing Study-D) is attributing the recidivism rates to ALL sex offenders against Prentky's WARNING, and makes no mention of the warning!
US Supreme court (Smith et al v. Doe et al, 2003, Sex Offender Registration): Brief filed by The State of California, Attorney General's office, and Attorney Generals of 43 other states Ex: Pg-8 "Prentky, et al., Recidivism Rates Among Child Molesters and Rapists: A Methodological Analysis, 21 Law & Hum. Behav. 635, 642-643 (1997). ... The studies indicate that sex offenders pose a risk of reoffending throughout their lives. "Contrary to conventional wisdom, most reoffenses did not occur within the first several years." Prentky, at 652. The "decay process" for rapists and child molesters is relatively slow and steady; offenders reoffend as late as twenty-four years after release from incarceration. ... In later years, the recidivism rate for child molesters actually increased. Prentky, at 651-653." Attorney Generals (43 of them) (citing Study-D) are attributing the recidivism rates to ALL sex offenders against Prentky's WARNING, and makes no mention of the WARNING!
King County Bar Association Article Ex: "The Narrow Population Subject to Civil Commitment: Although it is often reported that sex offenders have "low" recidivism rates relative to other inmate populations, a small percentage of sex offenders demonstrate persistent offending patterns throughout their lifetimes. In one of the few long-term studies of high-risk sex offenders, 52 percent of child molesters with extrafamilial victims and 39 percent of rapists with stranger victims committed new sexual offenses.4 (4 Dennis Doren, "Recidivism Base Rates, Predictions of Sex Offender Recidivism, and the 'Sexual Predator' Commitment Laws," 16 Behavioral Sciences and the Law (1998).)" (Washington State Bar Association)
State of New York, Dep't of Mental Health Ex: "Among sex offenders found to re-offend are pedophiles who prey on boys and rapists of adult women. In these cases, recidivism rates over a 25-year period of 52 percent and 39 percent, respectively, have been reported. 42 These individuals are often termed "sexually violent predators." "
Footnote: 42: Prentky R, Lee A, Knight R, & Cerce D. (1997). Recidivism rates among child molesters and rapists: A methodological analysis. Law and Human Behavior, 21, 635-659. (Study-D)