Quantifying Algorithmic Biases over Time

TL;DR

This paper introduces metrics to measure how algorithmic biases change over time, demonstrating that biases can vary significantly daily, which challenges static bias assessment methods.

Contribution

It proposes new metrics for tracking temporal variations in algorithmic bias and provides a case study showing biases fluctuate over a 21-day period.

Findings

Biases vary significantly over time.

Bias direction can change daily.

Static measurements may be insufficient.

Abstract

Algorithms now permeate multiple aspects of human lives and multiple recent results have reported that these algorithms may have biases pertaining to gender, race, and other demographic characteristics. The metrics used to quantify such biases have still focused on a static notion of algorithms. However, algorithms evolve over time. For instance, Tay (a conversational bot launched by Microsoft) was arguably not biased at its launch but quickly became biased, sexist, and racist over time. We suggest a set of intuitive metrics to study the variations in biases over time and present the results for a case study for genders represented in images resulting from a Twitter image search for #Nurse and #Doctor over a period of 21 days. Results indicate that biases vary significantly over time and the direction of bias could appear to be different on different days. Hence, one-shot measurements may not suffice for understanding algorithmic bias, thus motivating further work on studying biases in algorithms over time.