Offender risk assessments: Approaches to their development

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Research summary
Vol. 7 No. 2
March 2002


How do researchers approach the development of offender risk scales?


Differentiating offenders according to their risk to re-offend is important for many reasons. Of paramount importance is that knowledge of offender risk improves public safety by guiding decisions regarding control and supervision. In addition, differentiating offenders in terms of risk facilitates the delivery of treatment services to those most in need.

Research on offender risk scales has existed since the late 1920s. Different approaches have been used to develop these scales with varying degrees of success. After 80 years of research, a number findings have emerged that can guide researchers in developing better methods of assessing offender risk and assist correctional systems in choosing the most useful types of assessment.


A review of the issues surrounding offender assessment was conducted. The focus was on identifying the general factors to consider when developing and adopting risk scales for use with offenders.


One of the most consistent findings is that our ability to predict future criminal behaviour is enhanced when we base our predictions on statistical, research-based estimates of risk. This is called the actuarial approach. Historically, the professional judgements of risk typically given by psychiatrists and psychologists were preferred. It is now clear that clinical assessments do not perform as well as actuarial assessments in the prediction of future criminal behaviour.

Actuarial risk scales consist of items that are quantified and then added together to produce a summary score. Each item may be scored a value of 1 (factor present) or 0 (factor absent) and the total score related to the likelihood of an offender committing a new offence. A question that arises is how do we select what items, and how many, should be included in a risk scale.

Two approaches have been used in selecting items for inclusion. One approach takes risk factors identified by various studies and brings them together into a scale. Through statistical means, the number of items is then reduced to as few as possible without jeopardizing the overall validity of the scale. The other approach is to derive items from a theory of criminal behaviour and test these items against recidivism outcome.

Both approaches have advantages and disadvantages. The first approach usually produces brief risk scales comprised mainly of static, criminal history items. The second, theoretical approach usually produces a longer instrument that encompasses a range of information that includes dynamic factors (e.g., family problems, attitudes, employment difficulties). Although both approaches produce similar level of accuracy in prediction, the theoretical approach has the added benefit of identifying dynamic risk factors or the criminogenic needs of offenders. Criminogenic needs indicate areas where risk can be reduced and where treatment can be effective.

Policy implications

  1. Correctional systems that still rely on subjective, clinical assessments of offender risk should move toward actuarial assessments of risk. Actuarial risk assessment provides better prediction and service delivery
  2. Theory development has reached a level of maturity where theory can make a real contribution to the development of offender risk scales. An empirically supported theory of criminal behaviour can lead to assessment approaches that attend to offender needs and rehabilitation.
  3. Brevity in risk scales has a limited role in offender risk management. The longer, theory-driven risk scales, in addition to identifying the needs of offenders for programming purposes, also promote through their comprehensiveness a just and fair approach to citizens who come into conflict with the law.


For further information

James Bonta, Ph.D.
Public Safety Canada
340 Laurier Avenue West
Ottawa, Ontario
K1A 0P8
Tel 613-991-2831
Fax 613-990-8295

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