U.S. Department of Justice

Office of Justice Programs

Office of Juvenile Justice and Delinquency Prevention 

February 2002 #06

A new OJJDP Report provides technicians with a

statistical guide for preparing risk scales

Risk Classification: A Comparison of Methods for Practical Application in Juvenile Courts, a new Report from the Office of Juvenile Justice and Delinquency Prevention (OJJDP), details and

compares the processes for implementing a number of the most

commonly used statistical approaches in risk scaling. To help

technicians develop and use instruments to classify juveniles into

a small number of risk groups, the Report shows step-by-step procedures for developing a risk scale using several different statistical methods: a simple method without different weightings of the

predictive items, multiple linear regression, discriminant analysis,

logistic regression, and predictive attribute analysis.

Different statistical techniques were applied to a

common data set

For the Report, the authors constructed a data set from the automated records housed in the National Juvenile Court Data Archive

that held risk and criterion (outcome) information commonly

available in most jurisdictions. The data file captured the court

careers of 9,476 juveniles who had been referred to juvenile court

in a given calendar year and were between ages 8 and 15 at the

time of referral. In addition, the data file recorded whether the

juvenile had recidivated within 2 years of the referral date.

The authors show how they applied each statistical method to a

random portion of this data set (the construction sample) to produce an instrument that divided the referred juveniles into five

recidivism risk categories. The validity of each resulting risk instrument was assessed by applying it to the unused portion of

the original sample (the validation sample) and determining how

accurately the instruments and the resulting risk classifications

predicted the behavior of these youth.

Statistical Approaches 

to Assessing Risk

by Don M. Gottfredson and Howard N. Snyder

Risk scales are used to classify juveniles in the

justice system

Risk scales are statistical tools that help decisionmakers classify

juveniles on the basis of expected behavior. The juvenile justice

system commonly uses risk scales to predict a juvenile’s potential for recidivism or for successful program completion. Numerous factors (i.e., pieces of information) are incorporated into risk

scales, and they vary based on the population of juveniles to be

classified and the methods used to develop the scale. Much research has been done to identify the risk and protective factors

that should be incorporated into these scales. However, given the

limited capabilities of existing risk scales, it is clear that further

research is needed to uncover additional indicators of successful

outcomes and to assess different methods of scale development.

Technicians create risk scales from data

After a set of predictive factors is identified, either through

examining research or by tapping the expertise of experienced

professionals, decisionmakers (or, more precisely, their technical

staff) must decide how to combine these data into a score or risk

category that predicts future behavior. Over the years, many statistical methods have been used to prepare risk scales. Technicians, who can select from a set of possible data-reduction techniques, may consider the following questions: Which technique

is the most appropriate for the current situation? What are its

strengths and weaknesses? Are the results dependent on the

method selected? After answering these questions, technicians

can then process the raw data through a series of statistical procedures and create a straightforward paper-and-pencil instrument that line staff can use to reliably divide a population of

juveniles into subgroups that have different risk potentials. A

better understanding of the predictive capabilities of various statistical approaches to risk scaling should help technicians create

more effective risk classification systems.
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Techniques produced similar results, but some had

unique characteristics

The Report concludes that the predictive capabilities of the

risk scales, which were developed using the various statistical

approaches, were about the same. The authors address the differential benefits of each approach based on concerns beyond the

relative validity of the prediction scores: simplicity, the ease of

explaining the statistics to a nontechnical audience, and the ability to control for unwanted influences on the resulting prediction.

Risk Classification: A Comparison of Methods for Practical Application in Juvenile Courts provides the juvenile justice community and, more specifically, those charged with preparing a

risk classification instrument with a guide to preparing these

tools. Ideally, the Report will encourage those who were hesitant

to attempt to construct risk scaling instruments and will help

those who have done such work in the past to reconsider their

statistical methods.

For further information

A complete copy of Risk Classification: A Comparison of Methods

for Practical Application in Juvenile Courts by Don M. Gottfredson and Howard N. Snyder may be obtained by contacting the

Juvenile Justice Clearinghouse (800–638–8736). The Report

may also be downloaded in PDF format from the OJJDP Web

site (ojjdp.ncjrs.org). The work was funded by OJJDP’s National Juvenile Justice Data Analysis Project (grant number

1999–JN–FX–K002).

Don M. Gottfredson is the President of the Justice Policy Research Corporation, Sacramento, CA. Howard N. Snyder is the Director of Systems

Research at the National Center for Juvenile Justice, Pittsburgh, PA.

The Office of Juvenile Justice and Delinquency Prevention is a component

of the Office of Justice Programs, which also includes the Bureau of Justice

Assistance, the Bureau of Justice Statistics, the National Institute of Justice,

and the Office for Victims of Crime.

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