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Sexual Offence Recidivism: Prediction versus understandingFROM: Grubin,d & Wingate, S.; Criminal Behaviour and Mental Health, 6, 349-359 1996 Whurr Publishers Ltd. Pages 349 - 357DON GRUBIN AND SARAH WINGATE University of Newcastle/Newcastle City Health Trust,Newcastle upon TyneABSTRACT This paper identifies from the literature risk factors for reoffending in convicted sex offenders. Unless all sex offenders are to be incarcerated for indeterminate lengths of time, some means toseparate higher from lower risk men is clearly necessary. The complexities of the move fromidentifying high-risk groups to predicting risk in specific individuals is discussed. It is arguedthat the focus should be shifted from the search for single, putatively predictive variables to anattempt to understand why recidivism occurs.INTRODUCTIONWhen sex offenders reoffend the media interest and public anger that follow are often profound. This has been particularly evident in the United States where a number of sexual psychopathlaws have been passed in various states, usually after the commission of particularly notorioussex crimes by known offenders (Grubin & Prentky, 1993). A frequently discussed example ofthis is Washington State's Sexual Predator Act which allows for the civil commitment of sexoffenders for life if they are deemed to be sexual predators and likely to reoffend, together withcommunity notification when sex offenders are released from prison (Wettstein, 1992; Brodyand Green, 1994).Public concern about recidivism by sex offenders, however, is in contrast with the relatively lowlevels of sexual reoffending that are in fact the case. The tension between public perception ofsex offenders representing a high recidivism risk and the evident reality of statistics thatdemonstrate relatively low levels of sexual reoffending is in part influenced by a confusionbetween frequency and severity of reoffending, in part by the higher risk associated with someoffenders, and in part by the nature of sex offending itself where any reoffence may be seen asunacceptable. Fisher and Thornton (1993), for example, have observed that there are 'arelatively large number of offenders who offend at a low rate, perhaps even just once, and asmaller number who offend at a relatively high rate' (p. 108). Amongst this latter group will bemen whose reoffences are both frequent and severe. Some workers have argued that indefiniteincarceration is appropriate in this small number of cases (Harris, Rice & Quinsey, 1993), butthe difficulty is in accurately identifying those at most risk of serious reoffending whilstavoiding the unnecessary detention associated with false positive predictions.In theory, a greater understanding of what predicts sex offence recidivism would be beneficialnot only in deciding who needs to be locked up and for how long, but also in identifying thosewith particular treatment needs. But how can high-risk offenders be identified? Are actuarialapproaches using static demographic variables superior to clinical ones based on changingcircumstances and less quantifiable experience? Or is the prediction of sexual reoffending inspecific cases little more than a gamble based on an imperfect understanding of the relevantodds?SEX OFFENCE RECIDIVISMMost sex offenders are not reconvicted for sex offences. Kaul (1993), for example, cites a 1960sfollow-up of over 2900 Danish sex offenders (Christiansen, 1965) in which just 10% wereconvicted of another sex offence over a period of 12 to 24 years, although time at risk does notappear to have been considered in this study. A more recent UK report found that only 7% of arandomly selected sample of over 900 sex offenders (men with either current or past convictionsfor sex offences) released from prison in 1987 were reconvicted of a sex offence over the nextfour years (Marshall, 1994). Similarly, a meta-analysis involving 61 studies that included nearly29 000 sex offenders followed up on average for four to five years found that sexual recidivismwas 13% for child molesters and 19% for rapists, and reoffences of non-sexual violence 10%and 22% respectively (Hanson & Bussiere, 1995).These studies suggest that less than one in five of a general sample of sex offenders releasedfrom prison go on to commit a further sex offence. Similar figures are not available forconvicted sex offenders not sent to prison, but one would expect the recidivism rate to be evenlower in this group. Such low reoffending rates are in contrast with recidivism studies inreleased male prisoners in general amongst whom reoffending rates are in the range of 50% overtwo years and 60% over four (Home Office, 1994), though in a 15 to 30 year Canadian follow-upstudy of non-sexual criminals released from prison the recidivism rate was over 80% (Hanson,Scott & Steffy, 1995). These findings would appear to support West's (1987) claim that thetypical sex offender appears in court once and then never again, at least for further sex crime.Even when one looks at studies of apparently higher risk offenders, reoffence rates remainrelatively low. For example, in a sample of over 300 sex offenders who had committed moreserious offences (i.e. those who had received sentences of at least four years) released fromEnglish prisons in 1980, it was found that just 15% of rapists and about a third of child molesterswere reconvicted for a sex offence over the next 10 years (Thornton & Travers, 1991). Similarly, a large-scale research project in California designed to evaluate a sex offendertreatment programme for prisoners aimed at more serious offenders has had difficulty indemonstrating any impact of treatment because of the low base rate of reoffending in thenon-treatment controls: only 14% of 289 untreated child molesters and 14% of 80 untreatedrapists followed for an average of about four years had been rearrested (as opposed toreconvicted) for new sex offences (Marques, Day, Nelson & West, 1994; Marques personalcommunication).There are, of course, well-known difficulties in interpreting reoffending data, and it might beargued that the reoffences of sex offenders are less visible than those of other types of offender. First, although sexual reconviction rates are known to be proportional to actual offending rates(Hindelang, 1974), sex offences are generally under-reported, and most measures of sex offencerecidivism will be an under-representation of true reoffence rates. Marshall and Barbaree(1988), for example, found that unofficial records and contacts uncovered 2.4 failures, and 2.7victims, for every one documented by official statistics. Victim surveys imply even moreunreliability in the official data, suggesting that up to 80% of sex offences may go unreported(Mayhew, Elliot & Dowds, 1989).Undetected reoffences, however, are a problem for all recidivism studies. In terms of sexoffenders, even studies with intense follow-up that do not depend on convictions do not revealmassive numbers of reoffences (Marshall & Barbaree, 1988; Marques et al., 1994). If anything,the numbers of undetected offences by non-sex offenders are probably greater in relation tocrimes with higher base rates such as theft and general violence, particular given the fact thatonce an individual has been convicted of a sex crime he becomes known to the system..Another potential problem in interpreting recidivism studies is the length of follow-up. Soothilland Gibbens (1978), for example, followed 174 men convicted of sex offences against girlsunder 13 for 24 years. They found that 11% of the sample had been reconvicted of a sex orviolence offence over a five-year at-risk period, but by the end of the study the figure hadincreased to 18%, with no decrease in the level of severity. Other studies carried out by thisgroup in relation to rapists and incest offenders (Soothill, Jack & Gibbens, 1976; Soothill, 1980;Gibbens, Soothill & Way, 1981 ) suggest that these other types of sex offenders are also at riskof reoffending for many years. Similarly, a 15-year minimum follow-up of 197 child molestersreleased from Canadian prisons between 1958 and 1974 found that over this period 42% werereconvicted for sexual or violent crimes, but about a quarter of these reconvictions occurredbetween 10 and 31 years after prison release (Hanson, Steffy & Gauthier, 1993). The authors donot distinguish between sexual and violent offences in this study, but in a more recentlypublished analysis by the same group involving 191 of the child molesters, 35% werereconvicted of a sexual offence in the same follow-up period (Hanson, Scott & Steffy, 1995).Thus, whilst the base rate of the behaviour underlying sex offending may not be high, it ispersistent. It is important, however, to look more closely at those individuals whose reoffendingis delayed for many years. In the Soothill and Gibbens (1978) study, all the reoffending by menwith three or more previous convictions took place within five years, whilst those who did notreoffend for 10 years or more had just one or two prior offences. This suggests that long termfollow-up is less necessary amongst some groups of sex offenders than others. It appears thatshorter term follow-up is probably sufficient for more serious offenders, at least if a history ofthree or more previous convictions is taken as an indication of this (Thornton & Travers, 1991).Whilst one must be cautious when looking at recidivism data, those who downplay them are atrisk of overstating their case. Official statistics and follow-up studies in fact do appear to give areasonable though conservative estimate of the extent of reoffending by sex offenders. Whatthey make clear is that although sex offenders on the whole are not at great risk of reoffending,there is a need to identify the minority who are.PREDICTING SEX OFFENCE RECIDIVISMIt is often said that the best predictor of future behaviour is past behaviour. Various studies havedemonstrated that recidivism rates in first offenders range from 10% to 21% compared withrates of 33% to 71% in those with past convictions (Marshall, Jones, Ward, Johnston &Barbaree, 1991). Marshall's follow-up study (1994) of nearly 13 000 offenders of all typesreleased from prison in England and Wales in 1987, for example, found that men with a historyof sex offences were more likely to be convicted of a sex offence over the next four years thanthose with no history of sexual offending: 7% of released prisoners with such a history wereresponsible for 31% of the subsequent sex offence convictions, a highly significant finding. Thepractical importance of this finding in terms of actual numbers, however, is less impressive thanthe statistical significance would suggest. Of the 926 men with a history of sex offending, just61 (7%) were actually convicted of another sex offence, and though only 1% of the remainingsample were convicted of a sex offence, in real terms the latter 136 men represented twice asmany future sex offenders.Thus single variables, even those as important as a history of sex offending, are of limited use inpredicting sex offence recidivism. Nevertheless, supporters of actuarial approaches to theprediction of recidivism would argue that the problem is one of collecting enough of the rightvariables to plug into an algorithm that will generate a reliable desk-top prediction of risk ofsexual reoffending. For example, Quinsey and Walker (1992, P. 246) claim that 'enough workhas been completed to establish a general consensus within the research community about theclasses of variables that are valid predictors of recidivism'.What might these variables be? Most studies focus on static demographic and historical factorssuch as childhood abuse, parental instability, marital status, relationship to victim, and criminalconvictions. For example, Hanson, Steffy and Gauthier (1993) found that increased recidivismamongst child molesters was associated with never having been married and having previous sexoffences, whilst in rapists Thornton and Travers (1991) reported that reoffending related to acombination of a current or past conviction for violence, four or more previous convictions ofany sort, and age under 30 at the time of their sentences. Sugarman, Dumughn, Saad, Hinderand Bluglass (1994), in a study of exhibitionists, found that future contact sex offending couldbe predicted by childhood conduct disorder, early first conviction, criminal history, personalitydisorder and relationship difficulties.Other groups have added more dynamic variables to the equation, in particular sexual arousalpatterns. Rice, Harris and Quinsey (1990) found that both sexual and violent recidivism inrapists were well predicted by their phallometric (PPG) response to non-sexual violence inaddition to their score on the Hare Psychopathy Checklist. They claim, in fact, that these twovariables alone were as successful in predicting recidivism as the remainder of all the manydemographic, psychiatric, criminal and offence variables used in the study.These same workers in a later much more detailed actuarial study argued that a risk score basedon the interaction of nine variables produced an estimate of the probability of reoffending byserious sex offenders that, for those with high scores, approached one (Quinsey, Rice & Harris,1995). Not surprisingly, the variables accounting for most of the variance were the number ofprevious sex offence convictions and the number of previous prison sentences; the Harepsychopathy rating and deviant sexual arousal measured on PPG evaluation contributed onlymarginally to the variance, which is perhaps somewhat puzzling given their earlier claimsregarding these latter two variables.Statistically significant improvement in prediction does not necessarily translate into clinicalrelevance. In the Quinsey et al. study (1995), their algorithm was applied to a population ofnearly 180 sex offenders treated in a maximum security hospital. As the risk score increased, sotoo did reoffending, and overall the authors claim that their method resulted in 72% correctdecisions in relation to 'violent failure' and 77% correct decisions in relation to sexualreconvictions, both of which represented a relative improvement over chance of just over 40%. The vast majority of the sample, however, had risk scores giving a probability of reoffendingthat was less than 40%, which, even if a significant improvement over chance, is not particularlyhelpful to those who must make decisions about release. Thus, although the 50% success rate oftossing a coin to decide who was going to reoffend would not be as good as their method, itwould not be all that much worse. It is only for those with the highest scores that the probabilityof reoffending becomes clinically meaningful at around 85%, but this accounted for just sixmen, 3% of their sample.This study is perhaps the apotheosis of the actuarial approach, and as such it highlights well thefundamental defects inherent in it. First, it is wholly empirically driven and as such gives noreason to believe that findings from one population can be generalised to another. Second is theimplication that human beings are entirely a function of their histories: static historical data donot change, which means that regardless of treatment or maturity the risk of reoffending shouldremain unaltered. But both these objections are practical ones that can be overcome. The mostcrucial difficulty arises from the fact that actuarial prediction is about groups, and unless we aretalking about a high-frequency behaviour it can tell us little about individuals.Many of these issues have been discussed in relation to general reoffending in mentallydisordered patients (Gunn, 1993; Chiswick, 1995). The following example illustrates this lastpoint. Imagine that an actuarial technique is developed that can predict with 90% accuracy whowill reoffend and who will not, a figure much greater of course than anything currentlyavailable. Given 4000 sex offenders in prison with a recidivism rate of 10%, then 400 of thesemen will reoffend as opposed to 3600 who will not. With an actuarial tool of 90% accuracy, 360of the 400 reoffenders would be identified successfully (and just 40 missed). We would also,however, incorrectly decide that 360 (i.e. 10%) of the 3600 non-offenders will reoffend. Thus,we would identify a group of 720 men predicted to reoffend of whom just 360 (50%) willactually do so. What this means is that we would be making good decisions about who will notreoffend (in the above example, only about 1% of those let out would do so), and we wouldidentify well a high-risk group for continued detention, but for individuals within the high-riskgroup the odds of any one individual reoffending are still 50/50, that is, similar to tossing a coin.WHY DO PREDICTORS OF SEXUALRECIDIVISM PREDICT?Sex offenders are not simply bundles of variables. Characteristics that may be important toactuarials have little inherent meaning as they indicate associations but do not in themselvesimply causation. They become useful in understanding recidivism only when their possiblemeaning in particular individuals is clarified.In a review of violent recidivism, for example, Harris, Rice and Quinsey (1993) suggest thatyouth, marital status, psychopathy, criminal history, failure of prior conditional release, alcoholuse and antisocial conduct in childhood have been demonstrated consistently to be goodpredictor variables. But what does this mean other than that young, single, impulsive, violentmen, particularly when they drink, tend to behave in impulsive and violent ways? Similarly, inrelation to men who offend against children, Rice, Quinsey and Harris's (1991) finding thatreoffenders were more likely to have committed more sex offences, have more past prisonsentences, suffer from personality disorders, have never married, and be sexually deviant onphallometric assessment tells us little more than that strongly paedophilic men who are preparedto act on their sexual preferences will continue to seek out children for sex.In effect, variables like those described provide circular explanations for offending behaviour,and as such are of limited use in deciding whether an individual is likely to reoffend. Forexample, the reason why never-having been married is a good predictor of reoffending againstchildren could simply be that these men have little interest in forming relationships with women;even if they did subsequently marry, their risk of reoffending is unlikely to decrease (indeed, onewould be suspicious of such a man who suddenly announced his engagement, particularly if hisgirlfriend had children). The sample of men who have never married will include those withextreme deviance who cannot form such relationships, as well as those who may have a deficitin relation to their capacity for empathy, either of which could contribute causally to anindividual's offending.It may be, however, that being married does have a protective effect. Having a legitimate sexualpartner could mean that men are less likely to find themselves in situations where their risk ofoffending is increased as they no longer need to hunt for partners. Alternatively, the emotionalsupport of a spouse may decrease loneliness or feelings of inadequacy or rejection. Marshall(1989), and McKibben, Proulx and Lusignan (1994) describe the role of these negative emotionsin the chain leading to deviant sexual behaviours.Thus, the variable 'never having married' provides clinical utility only in so far as it tells ussomething about the personality and functioning of the man who displays it. Similarly, being inemployment has been found to be a protective factor (Marques et al., 1994). But is this causal innature, or is unemployment simply an indication that something else is not right?The danger of ignoring the meaning of variables and concentrating instead only on their effectsin particular studies is well illustrated in relation to the putative importance of the age of theoffender, where different studies produce contradictory results. Young age in general tends to bea predictor of all types of crime. There are of course a variety of reasons for this, ranging frompeer group pressure or incomplete socialisation to the fact that younger offenders may not havelearnt to avoid detection of their crimes as competently as their older counterparts. Thesefactors may also be at work in sexual offenders, explaining the findings of Thornton and Travers(1991) and Harris, Rice and Quinsey (1993), described above in relation to violent sex offenders. In contrast, Grunfeld and Noreik (1986) suggest that the effect of age on recidivism in sexualoffenders is diametrically opposed to that expressed in most of the literature, with youth carryinga favourable prognosis. They argued that sexual offences committed by older men were theresult of more deeply rooted tendencies or fixations that were unlikely to change over time. Clearly, post hoc explanations need to be treated with caution as plausible interpretations can begenerated to account for any contradictory theory or finding.The effect of age and its contribution to sexual offending and reoffending will only begin to beunderstood when it is treated as a richer concept than simply one to be plugged into recidivismequations. For instance, Richardson, Graham, Bhate and Kelly (1995) found that mostadolescent sex offenders displayed difficulty in containing their behaviours across severalaspects of their lives, demonstrated for example by truancy or aggression, and it is this, ratherthan an individual's age per se, that needs to be addressed. In order to predict future sexualdangerousness, it clearly will be necessary first to disentangle sexual psychopathology fromother antisocial behaviours, and then to gain a better understanding of the natural history ofeach.The most important predictor of sex offender recidivism is of course a history of past offending,both of a sexual and a general nature. This is often presented as a profound insight, but in realitythis variable does little more than distinguish a group of men who have demonstrated that theyare prepared to engage in particular behaviours. Similarly, those with more past offences havedemonstrated their willingness to carry on with their behaviours in spite of the risk ofapprehension, whereas in those who have only one or two such convictions this willingness willbe present in only some. But other factors may also be at work in relation to past offences. Ahistory of previous offending may increase the likelihood of future arrest as the individual willbe known to the police. Also, for some older sex offenders with previous prison sentences, lifeinside prison may have become preferred to life outside prison.In the large meta-analysis carried out by Hanson and Bussiere (1995), the predictive value of 69variables was tested. About one-third of these were significantly related to recidivism, andalthough the largest single predictor was the relatively dynamic variable of sexual preference forchildren as measured by phallometric methods, no variable was of sufficient strength to warrantits use in isolation.Unfortunately, meta-analysis is not particularly good at demonstrating multivariate effects,which require methodologies of a more complex type than one usually finds in follow-upstudies. One exception to this is the work of Malamuth and his colleagues (Malamuth, 1986;Malamuth, Sockloskie, Koss & Tanaka, 1991), who have reported that sexual violence inuniversity students followed up over 10 years is dependent on their sexual arousal in response toaggression, the extent to which dominance is a sexual motive for them, their hostility towardswomen, their attitudes to the acceptance of violence against women, their psychoticism and theirprior sexual experience. Their analysis, making use of path analytic and similar statisticaltechniques, demonstrates well the richness that can emerge when one moves away from lookingat single, static variables.The Malamuth work also demonstrates that more dynamic variables than those related to lifehistory can provide useful insights both in terms of understanding the causes of sexual offendingin particular individuals, and in identifying treatment targets. Factors such as affect, levels ofanger, general social skills, empathy and self-esteem may be crucial in specific cases, but theyare not easily quantifiable for the purposes of recidivism studies. In their meta-analysis,however, Hanson and Bussiere (1995) found that dynamic variables were notable in theirabsence from much of the research; in their large review of recidivism research, Furby, Weinrott& Blackshaw (1989) also noted a dearth of studies looking at dynamic as opposed to static riskfactors. This is partly because of difficulties in assessment, but also because by their very naturethey change over time, making quantification difficult.Whilst their changeable nature makes dynamic variables problematic from an actuarial point ofview, however, it is this very characteristic that makes them useful for predicting reoffending byindividuals in a clinical context. As Hanson and Bussiere (1995) point out, clinicians,particularly those involved in relapse prevention, have identified a number of factors such asanger, self-esteem and low victim empathy that may be important precursors to reoffending nearto the time when reoffending takes place (Pithers, Kashima, Cummings, Beal & Buell, 1988). Because it is state rather than trait that appears to be the most relevant in terms of reoffending,factors that tend to be invisible to the actuaries may be crucially important to clinicians indetermining when intervention is necessary.CONCLUSIONThere is a general consensus in the literature about those biographical variables that predictrecidivism, but there is much less discussion about why these variables have the effects they do. Overall, identification of those at low risk and those at exceptionally high risk of reoffending isgood, although prediction of the future offending behaviour of individuals in between is muchless satisfactory. For actuarial studies to have clinical relevance, they must also be shown to beable to contribute to risk assessment in specific cases, and to help formulate treatment needs. This will require movement away from a blind reliance on variables for their own sake to afuller understanding of how these variables relate to the phenomenon of sexual offending.ACKNOWLEDGEMENTSSW is supported by a grant from the Mental Health Foundation.REFERENCESBRODY, A. L. & GREEN. R. (1994). Washington State's unscientific approach to the problemof repeat sex offenders. Bulletin of the American Academy of Psychiatry and the Law 22,343-356. Return to Probation INDEX Click here to return to OCOI Homepagegeovisit();
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