Income and Democracy: A Smooth Varying Coefficient Redux
检验了收入对民主的影响，发现线性参数模型均被拒绝，但使用更灵活的非线性模型后，收入与民主的关系似乎受教育水平调节，且结果不显著。
Summary Acemoglu et al. ( American Economic Review 2008; 98 : 808–842) find no effect of income on democracy when controlling for fixed effects in a dynamic panel model. Work by Moral‐Benito and Bartolucci ( Economics Letters 2012; 117 : 844–847) and Cervellati et al. ( American Economic Review 2014; 104 : 707–719) suggests that the original model might have been misspecified and proposes alternative specifications instead. We formally test these parametric specifications by implementing Lee's ( Journal of Econometrics 2014; 178 : 146–166) dynamic panel test of linear parametric specifications against a general class of nonlinear alternatives robustly and reject all these specifications. However, using a more flexible model proposed by Cai and Li ( Econometric Theory 2008; 24 : 1321–1342) we find that the relationship between income and democracy appears to be mediated by education, but results are not statistically significant. Copyright © 2016 John Wiley & Sons, Ltd.