Income and Democracy
已有研究显示收入与民主在跨国数据中正相关，但本文加入国家固定效应后，发现收入对民主无统计关联，工具变量估计也表明收入不导致民主。
Existing studies establish a strong cross-country correlation between income and democracy but do not control for factors that simultaneously affect both variables. We show that controlling for such factors by including country fixed effects removes the statistical association between income per capita and various measures of democracy. We present instrumental-variables estimates that also show no causal effect of income on democracy. The cross-country correlation between income and democracy reflects a positive correlation between changes in income and democracy over the past 500 years. This pattern is consistent with the idea that societies embarked on divergent political-economic development paths at certain critical junctures.