Classification of Rapists in Massachusetts, 1980-1990 (ICPSR 9976)

Principal Investigator(s): Prentky, Robert A., Massachusetts Treatment Center; Knight, Raymond A., Massachusetts Treatment Center


The purpose of this study was to apply the latest version of a typological system for rapists (MTC:R3) developed at the Massachusetts Treatment Center for Sexually Dangerous Persons (MTC) to a large sample of offenders currently or previously incarcerated at MTC and to examine the system's reliability and concurrent and predictive validity. Data are available from two of the project's components. In the first component, 201 rapists who were committed to MTC between 1958 and 1981 were classified. This sample was used to revise the previous classification system (R2), upon which the development of the current system rests. Of these 201 men, 94 were in residence at the time of the study and 107 had been released. The second component classified a sample of 54 rapists who were committed after 1981. This sample was not used to develop the criteria for the typology. As an overview, this project had two missions: (1) to subtype about 250 rapists using MTC:R3 criteria, and (2) to utilize an archivally-derived database to examine the concurrent and predictive validity of the system. In addition to the subtype assignments, the primary source of data was the detailed institutional files that were used to code a 1,500-variable questionnaire.

Access Notes

  • One or more data files in this study are set up in a non-standard format, such as card image format. Users may need help converting these files before they can be used for analysis.

  • The public-use data files in this collection are available for access by the general public. Access does not require affiliation with an ICPSR member institution.


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Study Description


Prentky, Robert A., and Raymond A. Knight. CLASSIFICATION OF RAPISTS IN MASSACHUSETTS, 1980-1990. Compiled by the Massachusetts Treatment Center, Bridgewater, MA. ICPSR ed. Ann Arbor, MI: Inter-university Consortium for Political and Social Research [producer and distributor], 1994.

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This study was funded by:

  • United States Department of Justice. Office of Justice Programs. National Institute of Justice (88-IJ-CX-0021)

Scope of Study

Subject Terms:    alcohol, behavior problems, criminal histories, family histories, offender classification, rapists, sex offenders, sex offender profiles, treatment

Geographic Coverage:    Massachusetts, United States

Time Period:   

  • 1980--1990

Date of Collection:   

  • 1980--1990

Unit of Observation:    Individuals

Universe:    Male rapists committed to the Massachusetts Treatment Center for Sexually Dangerous Persons.

Data Type(s):    clinical data and event/transaction data

Data Collection Notes:

One record, which was determined to be a duplicate, was removed from the data file. Users are encouraged to obtain a copy of the Final Report for information on the development of the MTC:R3 typological system.


Study Purpose:    To facilitate clinical and forensic decisions about sex offenders, as well as to further an understanding of the etiology of sexual aggression, a programmatic effort to develop and validate taxonomic models to reduce the manifest heterogeneity among sexual offenders was undertaken. The present research grant had as its mission the testing and refinement of the second iteration of a taxonomic model for rapists (MTC:R3). Archival data were collected on 255 incarcerated rapists who had been classified according to MTC:R3. These data were used to examine the predictive and concurrent validity of the system.

Study Design:    This study applied the most recent version of a classification system for rapists to a sample of offenders that were currently or previously incarcerated at the Massachusetts Treatment Center (MTC) to assess the system's reliability and concurrent and predictive validity. This typology includes nine subtypes of rapists that are classified according to dimensions that are resumptively important in differentiating among rapists (e.g., generalized or global anger, misogynistic anger, eroticized anger, impulsive, antisocial personality, degree of preoccupation with gratification of sexual needs, and social competence). The nine subtypes in this prototypic system include: (1) Opportunistic offender with Low Social Competence, (2) Opportunistic offender with High Social Competence, (3) Pervasively Angry offender, (4) Overt Sadistic offender, (5) Muted Sadistic offender, (6) Sexualized, Nonsadistic offender with High Social Competence, (7) Sexualized, Nonsadistic offender with Low Social Competence, (8) Vindictive offender with Low Social Competence, and (9) Vindictive offender with Moderate Social Competence. The nine subtypes are ordered according to similarity of dendogram from a series of cluster analyses. This project used operational criteria for MTC:R3 to classify about 250 rapists, representing a model construction sample and a generalization sample. The system's reliability and concurrent and predictive validity were examined using an extensive archival database.

Sample:    The first sample consists of 201 rapists committed to MTC between 1958 and 1981. Of these 201 offenders, 107 had been discharged at the time of the study. In addition, this study included a generalization sample of 54 rapists committed after 1981.

Data Source:

archival data, including data previously obtained through structured clinical interviews

Description of Variables:    Both questionnaire ratings and classification judgments were made using the extensive clinical files that had been compiled over the years on all inmates committed to MTC. These files contained two primary sources of information: data gathered during a 60-day observation period when inmates were referred for evaluation and data added post-commitment on an inmate's institutional adaptation and progress in treatment. Post-commitment information routinely available included MTC records such as treatment progress reports, behavioral observation reports, work reports, summaries of program participation, results of psychometric assessments, and annual reports by an institutional review board. Information collected during the inmate's observation period included, in addition to diagnostic assessments and clinical interviews, data from multiple sources external to MTC, such as past institutionalization records, school and employment records, police reports, court testimony, parole summaries, probation records, and social service notes. These reports not only originated from different agencies, but were also written at different points in the inmate's life to describe events as they were occurring at that time. In many cases, social service and school reports that predated the inmate's first arrest or legal involvement were available. Access to these original reports helped to counteract the retrospective biases inherent in file research based largely on summary reports of a subject's life written after events of particular importance have already taken place (in this case, after the onset of criminal activity). Codings were made with the use of a questionnaire composed of three parts. The first part covered demographic information and the inmate's educational, occupational, military, medical, psychiatric, and criminal histories, as well as information pertaining to alcohol and drug use and detailed familial and developmental history. The second part of the questionnaire was comprised of a set of clinically derived scales that globally assessed the inmates on various aspects of social competence, aggression, antisocial behavior, and offense style. The third part of the questionnaire was a symptom checklist used to code the presence, severity, and/or chronicity of clinical and behavioral symptoms. The coded file data fall into six major categories: (1) demographic, (2) alcohol history, (3) family and developmental history, (4) criminal history, (5) clinical symptoms, and (6) major life events.

Response Rates:    Not applicable.

Presence of Common Scales:    None.

Extent of Processing:   ICPSR data undergo a confidentiality review and are altered when necessary to limit the risk of disclosure. ICPSR also routinely creates ready-to-go data files along with setups in the major statistical software formats as well as standard codebooks to accompany the data. In addition to these procedures, ICPSR performed the following processing steps for this data collection:

  • Performed recodes and/or calculated derived variables.
  • Checked for undocumented or out-of-range codes.


Original ICPSR Release:   1995-03-27

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