Differential treatment in the youth justice system - Equality and ...

Appendix D:Multivariate logistic regressionAPPENDICESThe following tables present the results of regression analysis that tested whether thereare differences in outcomes for young people of different ethnic groups controlling for arange of case characteristics. The model is based on a complete year (2006) of youngpeople who have been charged with an offence. This means that a young person canappear in the dataset more than once, and that individual cases were not independentof each other. This violates an assumption for logistic regression which often leads tounderestimated standard errors.To adjust for the dependent data, the statistical package STATA logistic regression withrandom effect was used, and the intra-class correlation (which is produced as part of themodel) was examined to see what proportion of the variance was explained by therepeated occurrence of the individual only. If this proportion was not significantly differentto zero, then it can be assumed that case characteristics have explained away allindividual effects and that results are similar to a logistic regression without controlling forthe repeated occurrence (produced using the statistical package SPSS). The Hausmantest was conducted on the logistic random effect model to test whether the model wasconsistent. In cases where the random effect model was shown to be inconsistent, but theintraclass correlation indicated that a proportion of the variance was explained by theindividual, then a logistic regression was run with clustered robust standard errors.Pre-court decisionsTo model pre-court decisions, we needed to identify all those young people who wereavailable for a pre-court disposal. We selected all young people who had scored less thanthree on the variable counting the number of previous convictions, provided that they hadpleaded guilty to the current offence. 61,62 This resulted in a sample of 5,325 boys and1,931 girls. The sub-sample did not precisely identify all those who received a pre-courtdisposal, identifying 87% and 89% of reprimands of boys and girls, and 76% and 78%of final warning for boys and girls. The variable ‘no previous convictions’ may provideunderestimates of young people with no previous convictions. For all cases involvingboys, 15% had no previous convictions, which is smaller than the 54.8% found by Feilzer6162The ‘guilty plea’ variable includes admissions of guilt made at police stations.We are aware that offenders with two previous convictions are ineligible for pre-court disposals, butour database shows that many such offenders received final warnings. We were unable to establishwhether the variable actually counts the number of contacts with the police and youth justice systemincluding the present contact – which would make sense of the pattern of findings that we haveseen.124