STATIC-99 and STATIC-2002 Instruments

The STATIC-99 and the STATIC-2002 are actuarial instruments that predict sex offender recidivism. They were designed to be widely applicable risk scales for the prediction of sexual recidivism that could be scored using commonly available file information from forensic settings such as prisons and forensic hospitals. Actuarial instruments for sex offender re-offense categorize sexual offenders into distinct risk levels such as low, moderate, and high risk to re-offend. Identifying the level of risk for sexual offenders improves the management of sexual offenders in the criminal justice system by allowing for appropriate level of supervision and treatment depending on risk level. Lower-risk sexual offenders may be placed on probation and participate in outpatient short-term treatment programs. A high degree of control supervision and intensive treatment can be allocated to sexual offenders identified as being higher risk to sexually re-offend. In more extreme cases, actuarial instruments can assist the evaluator in making decisions for the civil commitment of sexual offenders deemed to have a mental disorder that causes them to be too dangerous for release from custody and in need of inpatient treatment and custody.

The STATIC-99

The STATIC-99 was developed by R. Karl Hanson and David Thornton in 1999 to measure the prediction of violent and sexual recidivism. It is designed to be used for adult males who have already been charged with or convicted of at least one sexual offense against a child or a nonconsenting adult. The instrument is not appropriate for females or juvenile sexual offenders. The STATIC-99 is a combination of two existing actuarial scales for sexual recidivism: the Rapid Risk Assessment for Sex Offender Recidivism (RRASOR) and the Structured Anchored Clinical Judgment (SAC-J-MIN). As the name implies the scale contains only static risk factors, or historical risk factors, that have been found in research to predict sexual re-offense. The STATIC-99 was developed on three Canadian samples of sexual offenders from mental health and correctional facilities. Institut Philippe Pinel (n = 344) in Montreal provided long-term (1-3 years) treatment for sex offenders referred from both the mental health and correctional systems. Millbrook Correctional Centre (n = 191) is a maximum security provincial correctional facility located in Ontario, Canada. The Oak Ridge Division of the Penetanguishene Mental Health Centre (n = 142) in Ontario is a maximum security mental health center. The STATIC-99 was subsequently cross-validated on 563 sex offenders released from Her Majesty’s Prison Service (England and Wales) in 1979 and followed for 16 years.

The predictive validity of the instrument was measured by the receiver operating characteristic (ROC) curve. The STATIC-99 showed moderate predictive accuracy for both sexual recidivism (r = 0.33; ROC area = 0.71) and violent recidivism (r = 0.32; ROC area = 0.69).

The STATIC-99 includes 10 items that are scored as a 0 if not present and a 1 if present, except for the item prior sex offenses, which is scored 0 to 3. The items on the STATIC-99 include young age, single (ever lived with a lover for at least 2 years), index nonsexual violence (conviction), prior nonsexual violence (conviction), prior sex offenses, prior sentencing dates, any convictions for noncontact sex offenses, unrelated victims, stranger victims, and male victims. The score on the STATIC-99 can range from 0 to 12 and risk classifications include low, medium-low, medium-high, and high risk. Each risk level is associated with a probability of sexual re-offense for the study sample for 5, 10, and 15 years. Since the development of the STATIC-99, it has been repeatedly cross-validated in multiple jurisdictions and countries.

The STATIC-2002

In 2002, R. Karl Hanson and David Thornton revised the STATIC-99 in an effort to make the instrument simpler, more clinically applicable, and easier to score. The scale construction was designed to maximize the prediction of sexual recidivism. The selection of variables for the STATIC-2002 was guided by established research on factors that predict sexual recidivism as well as other empirically developed sex offender risk scales. The authors also included a number of exploratory variables that were supported by the constructs they were attempting to assess. Twenty-two individual variables with a simple bivariate relationship to sexual recidivism were organized into five content areas, including age at release, persistence of sex offending, deviant sexual interests, range of available victims, and general criminality. Multivariate analyses were used to determine whether the subscale added incrementally beyond the subscales already considered. Using Cox regression, each subscale was statistically weighted for its contribution to sexual recidivism.

The resulting scale was developed on a more diverse group of samples than the STATIC-99 and included two of the three developmental samples of the STATIC-99— Institut Philippe Pinel (n = 363) and Millbrook Correctional Centre (n = 186)—as well as three Canadian Federal Samples (n = 1229)—the California Sex Offender Treatment and Evaluation Project sample (n = 1137), the Special Sex Offender Sentencing Alternative (SSOSA) sample from Washington (n = 587), and the Manitoba Probation sample (n = 202). The STATIC-99/STATIC-2002 (ROC area = .71) showed levels of predictive accuracy for sexual recidivism similar to the STATIC-99 (ROC area = .69) for the prediction of sexual recidivism. The potential advantages of the STATIC-2002 over the STATIC-99 include improved prediction of violent recidivism over the STATIC-99, less variability than the STATIC-99 across settings, and more meaningful content areas when applied to clinical cases. Replication studies need to be conducted on large samples before it is possible to associate specific risk levels to specific ranges of scores as provided by the STATIC-99. The STATIC-2002 is a new instrument that needs to be replicated with independent data sets before it is appropriate for wide clinical use.

The items in the STATIC-2002 include the following: age at release; the persistence of sexual offending cluster with subsections including (a) prior sentencing occasions for sexual offenses, (b) arrests for sexual offenses as both an adult and a juvenile, and (c) rate of sexual offenses; the deviant sexual interests cluster with subsections including (a) any convictions for noncontact sexual offenses, (b) any male victims, and (c) two or more victims below the age of 12 with one victim unrelated; the relationship to victims of sexual offenses cluster including subsections (a) any unrelated victims and (b) any stranger victims; the general criminality cluster including subsections (a) any arrest/sentencing occasions, (b) any breach of conditional release, (c) years free prior to index offense, and (d) any prior conviction for nonsexual violence.

References:

  1. Hanson, R. K., & Thornton, D. (2000). STATIC-99: Improving risk assessments for sex offenders: A comparison of three actuarial scales. Law and Human Behavior, 24, 119-136.
  2. Hanson, R. K., & Thornton, D. (2003). Notes on the development of STATIC-2002. User Report 2003—01. Ottawa, ON, Canada: Department of the Solicitor General of Canada.

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