Learning Certifiably Optimal Rule Lists for Categorical Data
This provides a novel, interpretable alternative to decision tree methods for practitioners needing transparent models in domains like risk prediction.
The paper tackles the problem of building interpretable rule lists for categorical data by developing a custom discrete optimization technique that certifiably produces optimal training performance with orders of magnitude speedup and memory reduction, achieving results comparable to the COMPAS tool in seconds.
We present the design and implementation of a custom discrete optimization technique for building rule lists over a categorical feature space. Our algorithm produces rule lists with optimal training performance, according to the regularized empirical risk, with a certificate of optimality. By leveraging algorithmic bounds, efficient data structures, and computational reuse, we achieve several orders of magnitude speedup in time and a massive reduction of memory consumption. We demonstrate that our approach produces optimal rule lists on practical problems in seconds. Our results indicate that it is possible to construct optimal sparse rule lists that are approximately as accurate as the COMPAS proprietary risk prediction tool on data from Broward County, Florida, but that are completely interpretable. This framework is a novel alternative to CART and other decision tree methods for interpretable modeling.