Using Regression Kernels to Forecast A Failure to Appear in Court

TL;DR

This paper demonstrates that kernel regression methods, regularized with principal components, outperform stepwise logistic regression in forecasting failures to appear in court, especially with small to medium-sized datasets.

Contribution

The paper introduces a kernel-based regression approach for criminal justice forecasting tasks, showing improved accuracy over traditional logistic regression methods.

Findings

Kernel methods outperform logistic regression in FTA prediction.

Regularized kernel regression performs well with moderate-sized datasets.

The approach is implemented in the R package kernReg on CRAN.

Abstract

Forecasts of prospective criminal behavior have long been an important feature of many criminal justice decisions. There is now substantial evidence that machine learning procedures will classify and forecast at least as well, and typically better, than logistic regression, which has to date dominated conventional practice. However, machine learning procedures are adaptive. They "learn" inductively from training data. As a result, they typically perform best with very large datasets. There is a need, therefore, for forecasting procedures with the promise of machine learning that will perform well with small to moderately-sized datasets. Kernel methods provide precisely that promise. In this paper, we offer an overview of kernel methods in regression settings and compare such a method, regularized with principle components, to stepwise logistic regression. We apply both to a timely and important criminal justice concern: a failure to appear (FTA) at court proceedings following an arraignment. A forecast of an FTA can be an important factor is a judge's decision to release a defendant while awaiting trial and can influence the conditions imposed on that release. Forecasting accuracy matters, and our kernel approach forecasts far more accurately than stepwise logistic regression. The methods developed here are implemented in the R package kernReg currently available on CRAN.