Book contents
- Frontmatter
- Contents
- Preface
- Acknowledgments
- PART I AN INCREASED INCUMBENCY EFFECT: RECONSIDERING EVIDENCE
- PART II REALIGNMENT AND THE FORTUNES OF (SOME) INCUMBENTS
- PART III APPENDICES: MORE DETAILED ANALYSES OF INCUMBENCY EFFECT INDICATORS
- Appendix A Realignment and the Retirement Slump: A Closer Look
- Appendix B The Gelman-King Analysis
- Appendix C The Data Set
- Bibliography
- Index
Appendix B - The Gelman-King Analysis
Published online by Cambridge University Press: 06 July 2010
- Frontmatter
- Contents
- Preface
- Acknowledgments
- PART I AN INCREASED INCUMBENCY EFFECT: RECONSIDERING EVIDENCE
- PART II REALIGNMENT AND THE FORTUNES OF (SOME) INCUMBENTS
- PART III APPENDICES: MORE DETAILED ANALYSES OF INCUMBENCY EFFECT INDICATORS
- Appendix A Realignment and the Retirement Slump: A Closer Look
- Appendix B The Gelman-King Analysis
- Appendix C The Data Set
- Bibliography
- Index
Summary
One of the more commonly cited approaches to measuring the incumbency effect and its increase is that developed by Gelman and King (1990). The empirical results that their technique generates suggest that the incumbency effect began to increase in the 1960s and has remained relatively high since then. Given that their results indicate an increase and this book argues that there was not an increase, an analysis of their approach and results is in order.
Their concern is that existing measures of the incumbency effect (the sophomore surge and the retirement slump) are biased estimates. By their calculation, the sophomore surge underestimates the incumbency advantage by about 2 percentage points and the retirement slump overestimates the incumbency effect by about 2 percentage points (Gelman and King, 1990: 1147–49):
Even the most basic descriptive information about incumbency ad-vantage is flawed because every previous measure based on aggregate data…is plagued by selection bias, inconsistencies, and inefficiencies. We prove this result and also propose a new unbiased and statistically efficient measure that is very easy to calculate.
(Gelman and King, 1990: 1142)They define the incumbency advantage for an entire legislature as “the average of the incumbency advantages for all districts in a general election” (Gelman and King, 1990: 1143). To address their concerns of reducing bias and increasing statistical efficiency (Gelman and King, 1990: 1142, 1145–49, 1151), they present the following variable specifications and equation:
Denote v1 and v2 as the Democratic proportions of the two-party vote in elections 1 and 2, respectively. …Let I1 equal 1 if a Democratic incumbent runs for reelection, 0 if no incumbent runs, and −1 if a Republican incumbent is seeking reelection. […]
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- Reassessing the Incumbency Effect , pp. 130 - 150Publisher: Cambridge University PressPrint publication year: 2008