Difference-in-differences Design and Propensity Score Matching in Top Accounting Research: A Short Guide for Ph.D. Students in Iran

In recent years, to increase the robustness of methodology sections of accounting research, applying quasi-experimental methods has become a popular approach in archival-empirical research of top-tier accounting journals. The purpose of this study is to discuss the usefulness of the two most robust methods, including difference-in-differences (DD) and propensity score matching (PSM). This paper discusses DD and PSM design and reviews DD and PSM's use in articles of American Accounting Associations’ journals in recent years. In addition to a simple explanation of DD and PSM, this research provides a list of credible empirical accounting studies that have used these two methods. The research also explores the reasons for using the two methods in the empirical-archival studies of accounting and shows that in addition to extracting a causal relationship, the most important reason for using the two methods is to reduce the potential concerns surrounding the "omitted variables" "and "heterogeneity of treatment and control groups". Overall, by highlighting the importance and application of the DD and the PSM, this research can help the methodology sections' robustness in the empirical-archive accounting research that focuses on causal relationships and provide a simple and practical guide, especially for Ph.D. students in accounting.