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The Effects of Sanction Intensity on Criminal Conduct - JDAI Helpdesk

The Effects of Sanction Intensity on Criminal Conduct - JDAI Helpdesk

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We examine the potential interacti<strong>on</strong> <str<strong>on</strong>g>of</str<strong>on</strong>g> low-intensity supervisi<strong>on</strong> and pre-random<br />

assignment (RA) serious <str<strong>on</strong>g>of</str<strong>on</strong>g>fending <strong>on</strong> post-RA serious <str<strong>on</strong>g>of</str<strong>on</strong>g>fending for participants enrolled<br />

in the Low Risk Experiment using Mantel-Haenszel methods for calculating an adjusted<br />

risk ratio across different levels <str<strong>on</strong>g>of</str<strong>on</strong>g> a covariate. This is also a comm<strong>on</strong>ly-used approach in<br />

epidemiological research. First, we calculate the unadjusted risk ratio for the prevalence<br />

<str<strong>on</strong>g>of</str<strong>on</strong>g> post-RA <str<strong>on</strong>g>of</str<strong>on</strong>g>fending by assigned treatment. We then stratify by presence or absence <str<strong>on</strong>g>of</str<strong>on</strong>g><br />

pre-RA serious <str<strong>on</strong>g>of</str<strong>on</strong>g>fending, calculating two stratum-specific risk ratios. <str<strong>on</strong>g>The</str<strong>on</strong>g> Mantel-<br />

Haenszel method assigns a weight to each stratum and produces an adjusted overall risk<br />

ratio based <strong>on</strong> the weighted stratum-specific values. <str<strong>on</strong>g>The</str<strong>on</strong>g> accompanying Mantel-Haenszel<br />

chi-square test <str<strong>on</strong>g>of</str<strong>on</strong>g> homogeneity is used to c<strong>on</strong>sider whether an interacti<strong>on</strong> effect may be<br />

present. If χ 2 is statistically significant, we reject the null hypothesis <str<strong>on</strong>g>of</str<strong>on</strong>g> homogeneity <str<strong>on</strong>g>of</str<strong>on</strong>g><br />

the stratum-specific risk ratios.<br />

That is, we c<strong>on</strong>sider them sufficiently different to<br />

c<strong>on</strong>stitute evidence that the stratifying variable (serious <str<strong>on</strong>g>of</str<strong>on</strong>g>fending history) interacts with<br />

the independent variable (assigned treatment) to affect post-RA serious <str<strong>on</strong>g>of</str<strong>on</strong>g>fending<br />

outcomes. 7<br />

All analyses are c<strong>on</strong>ducted using the epidemiological methods suite in<br />

STATA 10.<br />

Sample characteristics<br />

We assess each <str<strong>on</strong>g>of</str<strong>on</strong>g> our four research questi<strong>on</strong>s using <strong>on</strong>e <str<strong>on</strong>g>of</str<strong>on</strong>g> two separate samples<br />

(‘full sample’ and ‘experimental sample’) drawn from the complete set <str<strong>on</strong>g>of</str<strong>on</strong>g> 3,207<br />

probati<strong>on</strong>ers described above.<br />

That dataset comprised 1,559 predicted low-risk<br />

experimental participants (800 LIS treatment and 759 SAU c<strong>on</strong>trol), 648 predicted low-<br />

152

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