Papers Omitted Variable Bias in Difference-in-Differences Designs Juejue Wang, Pedro Sant’Anna, Victor Chernozhukov, and Carlos Cinelli 2026 Working paper PDF Theses Comparison of Document Co-clustering Algorithms and Application of Single-cell RNA-seq Data Clustering to Twitter Data Juejue Wang 2021 Undergraduate honors thesis in Statistics, University of Michigan PDF Code Examination of the Reserve System for Medical Resource Allocation in Pandemics Juejue Wang 2021 Undergraduate honors thesis in Economics, University of Michigan PDF