Presidential Vetoes and Congressional Response: A Study of Institutional Conflict

Variance Specification in Event Count Models: From Restrictive Assumptions to a Generalized Estimator

“…l4 The key question for present purposes is the underlying process that generates the annual number of congressional challenges. If one were to collect data on individual challenges, this process could be modeled in the systematic component of the statistical model (see Rohde and Simon, 1985), but in the present data set this within-year process remains unobserved. Nevertheless, one can still theorize and test hypotheses about this process.…”

“…The domain for each observation may be a cross-section, a time interval, or even the cell of a contingency table. The number of visible uses of military force initiated by the United States in each six-month interval (Stoll, 1984), the number of presidential vetoes per year (Rohde and Simon, 1985), the frequency of formal and informal military alliances (Russett, 1971;McGowan and Rood, 1975), and the annual number of presidential appointments to the Supreme Court (King, 1987) are examples of time series counts. Examples of cross-sectional event count studies include the number of coups d'etat in each black African state (Johnson, Slater, and McGowan, 1984) and the number of political activities engaged in and reported by Soviet emigres (Di Franceisco and Gitelman, 1984).l *My thanks to Chris Achen, Jim Alt, Neal Beck.…”

A Seemingly Unrelated Poisson Regression Model

“…This article is concerned with analyses with two contemporaneously correlated event count variables; observations thus vary over both time and space-a pooled time-series crosssectional framework. Consider a few recent examples of univariate event counts: the number of consultations of a medical doctor for each survey respondent (Cameron and Trivedi, 1986), the number of triplets born in Norway in each half-decade (El-Sayyad, 1973), the number of presidential veto override attempts in the House and the number in the Senate per year (Rhode and Simon, 1985), the annual number of presidential appointments to the Supreme Court (King, 1987), the number of patents per firm (Hausman et al, 1984), the number of citizeninitiated and the number of support-related political activities engaged in and reported by Soviet emigres (Di Franceisco and Gitelman, 1984), the number of suicides per month, the number of spells of unemployment, and so on. There are numerous other examples from many disciplines.…”

War and the Reelection Motive

“…In fact, the constraints facing a president at any one time are more manifold than a basic ''election-on, election-off'' archetype. Work by Rhode and Simon (1985) suggests a leader's ability and latitude for pursuing a political agenda is highly sensitive to both popularity as well as partisan control of Congress; this is especially true during times of economic hardship. The authors show that the five most salient factors in explaining the use of presidential veto power are public approval, congressional seat proportion, international conflict, midterm election year, and an economic-political context interaction term, but not the presidential election year covariate.…”