How do discoveries of natural resources, such as oil reserves, affect a country's political institutions? This is an important question for students interested in international relations, public policies, and energy markets. Kevin Tsui uses a data set with 132 observations to answer this question using a few OLS regressions, reported below. The response variable in all regressions is the change in a country's political institutions, as measured by the Polity IV index - an index that ranges from -10 for an autocracy to 10 for a full democracy. The variable of interest among the explanatory variables is the amount of oil discovered in a country in the last decade, measured in 100 Giga barrels. Regression 1 is a single variable regression, looking only at the effect of oil discoveries on the change in Polity IV index. Regressions 2 and 3 are multi-variable regressions, including additional information about a given country. Standard errors of the coefficients are shown in parentheses below each coefficient. Ignore the stars on the coefficients

OLS OLS Variable (1) OLS (2) (3) Oil Discovered -0.075 -0.106 (per 100 Gb) -0.152 (0.030)** (0.038)** OilxDemocracy (0.045)** Before Discovery 0.283 Democracy Before (0.089)* * - -0.781 Discovery -0.823 (0.092)* * In (Income (0.094)* * - 0.117 Before Discovery) 0.114 In (Population (0.033)** (0.035)** - Before Discovery) 0.008 0.002 (0.014) Fraction Muslims (0.017) - -0.268 -0.217 (0.069)* * Ethnic (0.078)* * - -0.147 Fractionalisation -0.168 British Legal Origin (0.087)* (0.093)* - 0.020 0.036 Communist (0.052) (0.052) - -0.216 -0.180 Independent (0.057)** (0.063)** - 0.128 Before Discovery 0.091 (0.055)** (0.059)