A June 2026 NBER working paper examines whether employee reviews can reveal information about product and service quality before problems become visible externally. Wei Cai, Dennis Campbell, Yaxuan Chen, Yufei Chen and Andrea Prat use more than 4.3 million Glassdoor reviews to construct firm-level quality measures for S&P 1500 companies covering 2008 to 2023. The authors train machine-learning models using customer satisfaction information for a subset of firms and