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Deliberative Democracy: Testing for Endogeneity 1

APPENDIX II TO: “DELIBERATIVE DEMOCRACY: AN EMPIRICAL NOTE”

Testing for Endogenity in Caucus Variable July 5th, 2004 Paul Ma

The state/year dummies model specifications treat caucus as an exogenous variable. However caucus may be endogenously determined. For example one variable which could affect the likelihood of a state having caucuses is its population. Larger states tend to have more politi- cal activists with more money for such political events. Another may be the state’s educational level. More educated people may be less likely to go to caucuses because they can be informed via newspapers or other materials. On the other hand, more educated people may care more about the issues at hand, so the net effect is ambiguous. Time could also play a role in whether a state has a caucus. A state which had caucuses in the previous year would be more likely to have them again. From econometric literature however, adding lagged dependent variables can create serial correlation problems so we instead use year dummies. A panel data probit reveals that population and high school education are significant at the 5% level in affecting the probability of a state having a caucus. The year dummies are all sig- nificant as well at the 1% and 5% levels. Larger state populations seem to decrease the chances of the state having a caucus while having more graduated high school students has the opposite effect. After the probit estimation we create the inverse mills ratio which is a measurement of the selectivity bias associated with the endogenity of caucuses. One can see that from Table II, the mills ratio is insignificant, meaning that there is no selection bias. Even after accounting for selectivity bias, the caucus variable is still insignificant. The rest of the variables have the same signs and significances as from the equation of OLS with state and year dummies. From the data it appears that caucuses have no effects on voter participation. Deliberative Democracy: Testing for Endogeneity 2

Table II

Second Stage Heckit First Stage Probit Fixed Effects [1] [2] D.V. Caucus Vap

Population -0.02 (0.012)**

High School 0.047 0.36 (0.031)** (0.000)*** 1976 -1.2 -2.22 (0.005)*** (0.053)* 1980 -2.181 -4.46 (0.000)*** (0.025)** 1984 -1.453 -7.47 (0.005)*** (0.000)*** 1988 -2.467 -13.87 (0.000)*** (0.000)*** 1992 -2.923 -10.9 (0.000)*** (0.002)*** 1996 -3.77 -20.89 (0.000)*** (0.000)*** 2000 -4.022 -20.87 (0.000)*** (0.000)*** Caucus -0.48 -0.378

Age 20 to 24 -1.77 (0.000)*** Black -0.11 (0.000)*** Age 60+ 0.04 -0.887

Vote Ratio -0.02 -0.384 Income 0 -0.152 College 0.06 -0.761

Selectivity Bias -0.65 -0.389 Constant -1.71 52.41 -0.184 (0.000)***

Observations 408 408

Number of states 51 51 R-squared 0.421 p values in parenthe- Baseline year ses is 1972. * significant at 10%; ** significant at 5%; *** significant at 1%

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