The Unfairness of Popularity Bias in Music Recommendation: A Reproducibility Study

TL;DR

This study reproduces previous findings on popularity bias in recommender systems, specifically in music, revealing that popular items are favored and less popular users receive poorer recommendations, with some domain-specific differences.

Contribution

It extends prior work by reproducing and analyzing popularity bias in music recommendation, highlighting domain-specific effects and user group disparities.

Findings

Popularity bias favors popular music items in LastFM.

Low-mainstream users receive the worst recommendations.

Group Average Popularity metric shows different results in music domain.

Abstract

Research has shown that recommender systems are typically biased towards popular items, which leads to less popular items being underrepresented in recommendations. The recent work of Abdollahpouri et al. in the context of movie recommendations has shown that this popularity bias leads to unfair treatment of both long-tail items as well as users with little interest in popular items. In this paper, we reproduce the analyses of Abdollahpouri et al. in the context of music recommendation. Specifically, we investigate three user groups from the LastFM music platform that are categorized based on how much their listening preferences deviate from the most popular music among all LastFM users in the dataset: (i) low-mainstream users, (ii) medium-mainstream users, and (iii) high-mainstream users. In line with Abdollahpouri et al., we find that state-of-the-art recommendation algorithms favor popular items also in the music domain. However, their proposed Group Average Popularity metric yields different results for LastFM than for the movie domain, presumably due to the larger number of available items (i.e., music artists) in the LastFM dataset we use. Finally, we compare the accuracy results of the recommendation algorithms for the three user groups and find that the low-mainstreaminess group significantly receives the worst recommendations.