The SAGE Handbook of Research Methods in Political Science and International Relations offers a comprehensive overview of research processes in social science - from the ideation and design of research projects, through the construction of theoretical arguments, to conceptualization, measurement, and data collection, and quantitative and qualitative empirical analysis - exposited through 65 major new contributions from leading international methodologists. Each chapter surveys, builds upon, and extends the modern state of the art in its area. Following through its six-part organization, undergraduate and graduate students, researchers and practicing academics will be guided through the design, methods, and analysis of issues in Political Science and International Relations: Part One: Formulating Good Research Questions and Designing Good Research Projects; Part Two: Methods of Theoretical Argumentation; Part Three: Conceptualization and Measurement; Part Four: Large-Scale Data Collection and Representation Methods; Part Five: Quantitative-Empirical Methods; Part Six: Qualitative and Mixed Methods.
Chapter 43: Differences-in-Differences: Neither Natural nor an Experiment
Differences-in-Differences: Neither Natural nor an Experiment
When analysts seek to estimate causal effects, one of the most commonly used tools is differences-in-differences (DID). Widespread use of DID is most likely a result of two factors. One is that there are many cases where the method can be used. That is, it can be used in any context where before and after data exist for treated and control groups. Moreover, estimation can be done with linear regression models and, as such, no special software or programming is necessary. Another reason DID is widely employed is that many investigators assume that if one can apply DID, then the analysis tends be classified as a type of natural experiment. Evidence from natural experiments is now widely ...