The Static-99 and its revised form, the Static-99R (together referred to as Static-99/R), are static, actuarial risk assessment instruments. The Static99/R is designed for the evaluation of future reoffense risk among adult men, specifically those with a history of sexual offense convictions. It is comprised of 10 items which inventory the offending individual’s demographic characteristics and criminal conviction history and the characteristics of the sexual offense victim. Although originally developed in English, the Static-99R has since been translated into several different languages including Chinese, French, and German. At present, the Static-99/R is the most widely used sexual offense risk assessment instrument in the world. This article briefly addresses the history of the Static-99/R, then examines the Static-99/R items, criteria for use, and guidelines for interpreting scores.
History
The name Static-99 is derived from 1999, the development year of its original form, and its focus on static, or unchanging, risk factors associated with future sexual or violent offense behavior. It was originally developed following analyses of two separate risk assessment tools: the Rapid Risk Assessment of Sex Offender Recidivism and the Structured Anchored Clinical Judgment- Minimum. Each provided statistically unique contributions to recidivism risk estimates, and a 10-item amalgamation was assembled from these two instruments. In 2009, research demonstrating a correlation between increased age and reduced recidivism risk drove a change in the age item from two categories to four. This represented enough of a substantive change to rename the instrument the Static-99R (i.e., the revised version).
Static-99/R Items
The Static-99/R is completed using information drawn from the offending individual’s demographics and criminal history, and sexual offense victim demographics. Some of the Static-99/R items are relative to the index sexual offense, that is, the most recent sexual offense (usually the current offense) for which the individual has been convicted and sentenced.
Age at release from index sex offense refers to the individual’s age upon placement in the community. This may be the offender’s age when sentenced to community supervision in lieu of incarceration or the offender’s age at release from jail or prison. The Static-99 only differentiated between younger and older individuals. The Static99R updated this item to include multiple age cutoffs; research has illustrated recidivism risk reduces with age.
Ever lived with a lover queries the individual’s history of maintaining cohabitation with an age-appropriate intimate partner for at least two uninterrupted years. This is believed to reflect skills associated with reduced sexual offending behavior (e.g., the ability to develop prosocial relationships and engage in interpersonal problem-solving).
Index nonsexual violence—any convictions is counted for any specific convictions for a violent, nonsexual crime, prosecuted concurrent to the index sexual offense. This may include convictions for assault, murder, kidnapping, or robbery. Similarly, Prior nonsexual violence—any convictions counts convictions prior to the index offense sanction. While such nonsexual, violent behaviors are often associated with future criminal behavior, these items do not include arrests or charges that do not result in convictions, institutional rule violations, or self-reports of nonsexual violence.
Prior sex offenses includes sexual offense arrests, charges, and convictions recorded prior to the index offense sanction. The number of arrests, charges, and convictions, including those as a juvenile, is converted into a prior sex offense score, depending on the number of each type of sanction. Pseudo-recidivism (i.e., historic offenses adjudicated after the index sexual offense) is not counted toward this score.
Prior sentencing dates counts the number of unique sentencing episodes for any offense prior to the index offense sanction. Four or more prior sentencing episodes are weighted toward increased recidivism risk.
Any convictions for noncontact sex offenses is scored if the individual has been convicted of offenses including exhibitionistic or voyeuristic behavior, offenses related to child pornography, or obscene use of a communications device.
The remaining items, any unrelated victims, any stranger victims, and any male victims, are described as the three victim questions. Scoring these items may be based on official information related to the offense but also based on an individual’s self-report or other information the evaluator deems credible.
Criteria for Use
The Static-99/R is an actuarial risk assessment tool, and as such, its primary purpose is to inform evidenced-based estimates of recidivism risk. Formal research on the Static-99/R has focused on adult men who have been legally sanctioned for an offense that is sexual in nature. The Static-99/R is not typically recommended for use with juvenile males who commit sexual offenses and is not recommended for use with female sexual offenders.
A number of criteria adopted by many sexual offense risk assessment instruments originated from or were popularized by the Static-99/R. What follows is a discussion of several key criteria.
Legal Sanctions
To qualify for a Static-99/R scoring, an individual must have been legally sanctioned for some criminal sexual behavior, which includes a number of possible legal classifications. While court proceedings involving sexual offenses often result in convictions for a sexual crime, there are many situations in which a specific sexual crime conviction is not achieved, such as a defendant being found not guilty by reason of insanity. Such a criminal charge is still considered a legal sanction necessary for Static-99R use. An arrest for sexually motivated criminal behavior may be classified as a qualifying legal sanction as well; even if the individual is not charged for an offense which is sexual in nature, there can be enough evidence to substantiate a sexual motive or quality to the behavior. Other legal sanctions include institutional disciplinary actions for nonconsensual sexual behavior and violations of probation, parole, or other forms of community supervision.
Offense Categories
The Static-99/R classifies sexual offenses into two categories. Category A offenses include those sexual behaviors involving any child or a nonconsenting adult victim, including rape, child molestation, or exhibitionist behavior. Category B offenses involve legally consented, criminal sexual behavior, including consenting sexual activity between adults in public, or behavior that does not involve an identifiable victim (e.g., behaviors involving child pornography). Individuals who have never been sanctioned for Category A offenses in their lifetime cannot be scored on the Static-99/R.
The Index Offense
A key component of scoring the Static-99/R is the index offense. The index offense is the most recently sanctioned sexually offense. This may include any new Category A offense, or a Category B offense committed by those sanctioned for Category A behavior in the past. The index offense also contributes to the time reference for the recidivism risk estimates provided by the Static-99/R.
Many individuals’ sexual offense histories are complicated, though, and an individual being scored on the Static-99/R may have multiple recent sexual offense sanctions. The following two classifications for multiple offense types have been identified:
Index clusters—An index cluster is identified most simply as several offenses committed during the same period of time. These multiple offenses are investigated and prosecuted as a group, often appearing as a spree, or cluster, in one court episode on a criminal record review. Variants of the index cluster are determined by the evaluator scoring the Static-99/R. For example, these offenses may occur in multiple areas, thus causing court proceedings in different jurisdictions. Alternatively, multiple offenses may not all be uniformly identified by the authorities, but nevertheless their proximity in time qualifies these offenses as a cluster.
Pseudo-recidivism—Pseudo-recidivism refers to new sanctions for sexual offending behavior that is substantially older than the index offense. Many sexually offending individuals have previous sexual offenses which are unreported for a variety of reasons but later come to light following the official index sanction. For example, the publicity surrounding an individual’s conviction for sexual abuse may encourage victims of previously unreported offenses to come forward about their experiences. As these offenses were never sanctioned before the index offense, they are not counted toward prior sexual offense convictions. Pseudo-recidivism is a class of index cluster but differs from other index clusters in that the time factor between the early offenses and the index offense is distal, not proximal.
Interpreting Static-99/R Scores
The Static-99/R raw score is derived from summation of the 10 items, without further scaling or adjustment. The Static-99’s scores ranged from 0 to 12, while the Static-99R range is from −3 to 12. There are multiple applications of this score to determine the risk of sexual recidivism as well as nonsexual violent recidivism, for a specific individual score on this instrument.
As an actuarial risk assessment instrument, the Static-99/R predicts the probability that a sexually offending individual will be sanctioned again for another offense. For a specific Static-99/R score, several ways of reporting this probability are available. Observed recidivism rates are available from a number of sources; given the lower prevalence of some offender types (e.g., relatively high-risk offenders), a type of statistical modeling known as logistic regression may be used to estimate the rate of recidivism associated with a specific score. Alternatively, the risk ratio for a specific score may be reported. The risk ratio is the individual’s odds of recidivism against a reference point for the offender population (e.g., the median score of all offenders). These recidivism data are often based on the likelihood of reoffense 5 or10 years following placement in the community after the index offense.
A key consideration in assessing recidivism predictions is the application of data from an appropriate sample. Users of the Static-99/R must consider the population from which a sexually offending individual originates, then draw conclusions about risk based on information from a sample which most closely fits this population. Some jurisdictions may choose to survey their own population and develop specific, appropriate risk information or norms. However, the Static-99/R undergoes regular evaluation, which includes updating norms based on multiple aggregated samples of offenders. The developer-provided risk norms fall into two categories: routine and preselected high risk. The use of preselected high-risk norms is based on information exclusive from the Static-99/R score, which indicates an individual presents greater recidivism risk than is typical for that individual’s Static-99/R score. An example of this includes elevated scores on a separate dynamic risk assessment tool.
It is necessary to be aware of population characteristics to ensure information provided by the Static-99/R is statistically valid in risk assessments. The primary method of evaluating the statistical accuracy of the Static-99/R is the area under the receiver operating characteristic curve (AUC) statistic. This statistic ranges in value from 0 to 1.0; an AUC of 1.0 shows perfect prediction, whereas an AUC below 0.5 implies more incorrect than correct predictions. A comprehensive meta-analysis of Static-99/R research found an overall AUC between 0.69 and 0.70, which essentially means that there is a 69–70% probability that a randomly selected sexual recidivist will have a higher Static-99/R score than a randomly selected nonrecidivist. However, the AUC value can vary significantly between different populations; ensuring the Static-99/R is valid within a specific population is of paramount concern in risk evaluations.
Static-99/R consecutive scores may be clustered into relative risk categories, traditionally defined as low, low-moderate, moderate-high, and high risk of recidivism. As of 2016, the recommended classification of Static-99R scores involved qualitatively categorizing scores which correlate with psychologically meaningful criteria. A five- category system is used which clusters offenders not solely on the probability of a new offense but on the characteristics of those who fall into a given category. Static-99R scores of 1–3 comprise Category III or the average risk category. This suggests individuals in this group are within the average likelihood range of recidivism risk of their jurisdiction. Category-I and Category-II offenders encompass Static-99R scores of −3 to −2 and −1 to 0, respectively, and are typically older and less involved with the criminal justice system than the average risk offender. Category IV-a includes scores of 4 or 5, and Category IV-b includes scores of 6 and above. Each increased level is typically indicative of greater history with the criminal justice system, violent offenses, and other factors associated with persistent sexual offending (e.g., offenses against strangers). These categories more easily communicate an individual’s risk potential, while being less subject to differences between jurisdictions or between methods of evaluation.
References:
- Hanson, R. K., Babchishin, K. M., Helmus, L. M., Thornton, D., & Phenix, A. (2016). Communicating the results of criterion referenced prediction measures: Risk categories for the Static-99R and Static-2002R sexual offender risk assessment tools. Psychological Assessment. Advance online publication. doi:10.1037/pas0000371
- Hanson, R. K., Thornton, D., Helmus, L. M., & Babchishin, K. M. (2016). What sexual recidivism rates are associated with Static-99R and Static-2002R scores? Sexual Abuse: A Journal of Research and Treatment, 28(3), 218–252. doi:10.1177/1079063215574710
- Helmus, L., Hanson, R. K., Thornton, D., Babchishin, K. M., & Harris, A. J. R. (2012). Absolute recidivism rates predicted by Static-99R and Static-2002R sex offender risk assessment tools vary across samples: A meta-analysis. Criminal Justice and Behavior, 39(9), 1148–1171. doi:10.1177/0093854812443648
- Helmus, L., Thornton, D., Hanson, R. K., & Babchishin, K. M. (2012). Improving the predictive accuracy of Static-99 and Static-2002 with older sex offenders: Revised age weights. Sexual Abuse: A Journal of Research and Treatment, 24(1), 64–101. doi:10.1177/1079063211409951
- Phenix, A., Fernandez, Y., Harris, A. J. R., Helmus, M., Hanson, R. K., & Thornton, D. (2016). Static-99R coding rules revised—2016: In-press version (14-Nov2016). Retrieved from http://static99.org/pdfdocs/ Coding_manual_2016_v2.pdf
- Phenix, A., Helmus, L. M., & Hanson, R. K. (2016). Static-99R & Static-2002R evaluators’ workbook. Retrieved from http://static99.org/pdfdocs/Evaluators_Workbook_2016-10-19.pdf