Quantitative Criminology


1. Introduction

2. Quantitative Data Sources

3. Logical and Inferential Issues

3.1. Time Horizon

3.2. Unit of Analysis

3.3. Sampling

3.4. Target Population

3.5. Concepts and Variables

3.6. Descriptive and Causal Inference

3.7. Validity

3.8. Reliability

3.9. Relationship Between Reliability and Validity

3.10. Estimates and Estimators

3.11. Estimator Properties: Bias, Efficiency, and Consistency

4. Assessing Evidence

5. Methods for Descriptive Inference

5.1. Measures of Central Tendency

5.2. Measures of Dispersion

5.3. Criminal Careers

5.4. Recidivism Rates

5.5. Trajectories and Developmental Pathways

6. Analytic Methods for Causal Inference

6.1. Independent Variables and Outcomes

6.2. Contingency Tables

6.3. Measures of Association

6.4. Chi-Square, t Tests, and Analysis of Variance

6.5. Linear Regression

6.6. Regression for Qualitative and Counted Outcomes

6.7. Structural Equation Models

6.8. Interrupted Time Series Analysis

6.9. Models for Hierarchical and Panel Data

6.10. Counterfactual Reasoning and Treatment Effects

6.11. Randomized Experiments

6.12. Natural Experiments and Instrumental Variable Estimators

6.13. Matching

7. Conclusion

1. Introduction

Since its inception as a field of scientific inquiry, criminology and criminal justice (CCJ) researchers have used quantitative data to describe and explain criminal behavior and social responses to criminal behavior. Although other types of data have been used to make important contributions to criminological thought, the analysis of quantitative data has always played an important role in the development of knowledge about crime. This research paper discusses the various types of quantitative data typically encountered by CCJ researchers. Then, some of the logical and inferential issues that arise when researchers work with quantitative data are described. Next, the research paper considers different analytic frameworks for evaluating evidence, testing hypotheses, and answering research questions. Finally, a discussion of the range of methodological approaches used by contemporary CCJ researchers is provided.

2. Quantitative Data Sources

CCJ researchers commonly work with data collected for official recordkeeping by government or quasi-government agencies. Such data often include records of criminal events, offender and victim characteristics, and information about how cases are handled or disposed. Detailed information about crimes known to the police and crimes cleared by arrest are available in the UniformCrime Reports (UCR) and the National Incident Based Reporting System (NIBRS). In addition, for purposes of specific research projects, criminal justice agencies often make their administrative records available to criminologists—provided that appropriate steps are taken to protect individual identities. For example, the Bureau of Justice Statistics has conducted two major studies of recidivism rates for prisoners returning to the community in multiple states. Such projects require coordinated use of state correctional databases and access to criminal records, including arrests, convictions, and reincarceration.

More recently, researchers have also relied on information collected through direct interviews and surveys with various populations. In these surveys, respondents are asked about their involvement in offending activities, victimization experiences, background characteristics, perceptions, and life circumstances. Analyses from data collected through the National Crime Victimization Survey; the Arrestee Drug Abuse Monitoring program; the RAND inmate survey; the National Youth Survey; the National Longitudinal Survey of Youth; the Adolescent Health Study; Monitoring the Future (MTF); Research on Pathways to Desistance, and the Office of Juvenile Justice and Delinquency Prevention’s longitudinal youth studies in Rochester, New York, Pittsburgh, Pennsylvania, and Denver, Colorado, have all made important contributions to criminological thought and public policy.

Researchers have also attempted, in some studies, to collect detailed quantitative databases composed of information from both administrative and direct surveys on the same individuals. Among other findings, this research has consistently shown that most crime victimizations are not reported to the police and that most offending activities do not result in an arrest.