•   When: Thursday, April 06, 2023 from 11:00 AM to 12:00 PM
•   Speakers: Amanda Coston
•   Location: ENGR 4201
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Abstract: 

Machine learning algorithms are widely used for decision-making in societally high-stakes settings from child welfare and criminal justice to healthcare and consumer lending. Recent history has illuminated numerous examples where these algorithms proved unreliable or inequitable. In this talk I show how causal inference enables us to more reliably evaluate such algorithms’ performance and equity implications. 

In the first part of the talk, I demonstrate that standard evaluation procedures fail to address missing data and as a result, often produce invalid assessments of algorithmic performance. I propose a new evaluation framework that addresses missing data by using counterfactual techniques to estimate unknown outcomes. Using this framework, I propose counterfactual analogues of common predictive performance and algorithmic fairness metrics that are tailored to  decision-making settings. I provide double machine learning-style estimators for these metrics that achieve fast rates & asymptotic normality under flexible nonparametric conditions. I present empirical results in the child welfare setting using data from Allegheny County’s Department of Human Services.

In the second half of the talk, I propose novel causal inference methods to audit for bias in key decision points in contexts where machine learning algorithms are used. A common challenge is that data about decisions are often observed under outcome-dependent sampling. I develop a counterfactual audit for biased decision-making in settings with outcome-dependent data.  Using data from the Stanford Open Policing Project, I demonstrate how this method can identify racial bias in the most common entry point to the criminal justice system: police traffic stops. To conclude, I situate my work in the broader question of governance in responsible machine learning. 

Bio:  Amanda Coston is a PhD student in Machine Learning and Public Policy at Carnegie Mellon University. Her research investigates how to make algorithmic decision-making more reliable and more equitable using causal inference and machine learning. Prior to her PhD, she worked at Microsoft, the consultancy Teneo, and the Nairobi-based startup HiviSasa. She earned a B.S.E from Princeton in computer science with a certificate in public policy.  Amanda is a Meta Research PhD Fellow,  K & L Gates Presidential Fellow in Ethics and Computational Technologies, and NSF GRFP Fellow, and has received several Rising Star honors.