Criminal Specialization Revisited: A Simultaneous Quantile Regression Approach

Whether criminals are specialized or versatile in their offending is a long-standing research area that has been recently revitalized by a paradigm that recognizes that both specialization and versatility characterize offending careers. Based on data from an enriched sample of 500 adult habitual criminals, the current study introduces a measure of relative specialization-the offense specialization coefficient-and a novel analytical technique called simultaneous quantile regression to further the study of specialization. Although offenders committed a mix of offenses, there was considerable and at times pronounced evidence of specialization. Age, sex, and arrest onset had differential predictive validity of specialization for eight crimes at the 75th and 95th quantiles. Implications and suggestions for future research are offered.