Matthew J.H. Murphy

mjhm[at]sas.upenn.edu

I am an economic theorist studying learning and digital economies. My current research primarily focuses on how technological changes influence market structure and producer incentives. My CV can be found here.

Clicks or Comments? The quality-quantity trade-off of review systems

2026

Abstract PDF Slides

I study the optimal design of review systems. A platform learns a product’s quality from user-generated reviews. It faces a trade-off between the informativeness and frequency of reviews. Detailed reviews are individually more informative but less frequently submitted than simple reviews. I characterize the informational content of review systems, which depends on the information in each review and their submission rate. I use this characterization to derive the platform’s optimal review system and show how it varies with reviewers’ preference heterogeneity. In particular, when reviewers are homogeneous the platform isolates “horrible" experiences instead of differentiating between “good" and “bad" experiences.
Market Structure and the Distribution of Content

2026

Abstract Slides

I study how market structure influences the distribution of entertainment products. When producers compete for attention, ex-ante uncertainty over their quality causes producers to inefficiently sort across horizontally differentiated products (“genres"). In the competitive equilibrium, production is inefficiently concentrated in high-demand, homogeneous, genres. Flat pricing alleviates this inefficiency when genres are ex-ante similar in quality, but aggravates this inefficiency when genres are ex-ante different. Merging producers into an integrated platform restores efficiency. Recommendation systems are able to sometimes improve on the competitive equilibrium by suppressing some content.