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  • PhD Thesis Defense - Basileal Yoseph Imana

    Tue, Aug 15, 2023 @ 11:00 AM - 01:00 PM

    Thomas Lord Department of Computer Science

    University Calendar

    PhD Thesis Defense - Basileal Yoseph Imana

    Committee Members: John Heidemann (Chair), Aleksandra Korolova, Bistra Dilkina, Phebe Vayanos

    Title: Platform Supported And Privacy Preserving Auditing of Social Media Algorithms For Public Interest

    Social media platforms are entering a new era of increasing scrutiny by public interest groups and regulators. One reason for the increased scrutiny is platform induced bias in how they deliver ads for life opportunities with legal protections against discrimination. Platforms use relevance estimator algorithms to optimize the delivery of ads. Such algorithms are proprietary and therefore opaque to outside evaluation, and early evidence suggests these algorithms may be biased or discriminatory. In response to such risks, the U.S. and the E.U. have proposed policies to allow researchers to audit platforms while protecting users privacy and platforms proprietary information. Currently, no technical solution exists for implementing such audits with rigorous privacy protections and without putting significant constraints on researchers. In this work, our thesis is that relevance estimator algorithms bias the delivery of opportunity ads, but new auditing methods can detect that bias while preserving privacy.

    We support our thesis statement through three studies. In the first study, we propose a black box method for measuring gender bias in the delivery of job ads with a novel control for differences in job qualification, as well as other confounding factors that influence ad delivery. Controlling for qualification is necessary since qualification is a legally acceptable factor to target ads with, and we must separate it from bias introduced by platforms algorithms. We apply our method to Meta and LinkedIn, and demonstrate that Metas relevance estimators result in discriminatory delivery of job ads by gender. In our second study, we design a black box methodology that is the first to propose a means to draw out potential racial bias in the delivery of education ads. Our method employs a pair of ads that are seemingly identical education opportunities but one is of inferior quality tied with a historical societal disparity that ad delivery algorithms may propagate. We also develop a method for auditing ad delivery using inferred race that handles uncertainty in inference. Using inferred race is useful to address the lack of access to race attributes that is a growing challenge for auditing racial bias in ad delivery. We evaluate Metas delivery of education ads with both known and inferred race. When race is known, we demonstrate Metas relevance estimators racially bias the delivery of education ads. We then show, when race is inferred, inference error makes the test for bias in ad delivery less sensitive to small amounts of bias. Going beyond the domain specific and black box methods we used in our first two studies, our final study proposes a novel platform supported framework to allow researchers to audit relevance estimators that is generalizable to studying various categories of ads, demographic attributes and target platforms. The framework allows auditors to get privileged query access to platforms relevance estimators to audit for bias in the algorithms while preserving the privacy interests of users and platforms. Overall, our first two studies show relevance estimator algorithms bias the delivery of job and education ads, and thus motivate making these algorithms the target of platform supported auditing in our third study. Our work demonstrates a platform supported means to audit these algorithms is the key to increasing public oversight over ad platforms while rigorously protecting privacy

    Location: Henry Salvatori Computer Science Center (SAL) - 213

    Audiences: Everyone Is Invited

    Contact: Melissa Ochoa

    Event Link: https://usc.zoom.us/j/93768511444?pwd=dDZTVjdyM0trSE1Qc2dqQ2hMcWNxUT09


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