I have a dependent variable (Gini coefficient) with values between 0 and 1 (e.g. 0.3244, 0.5648, 0.9972, etc.).
Do you know what kind of regression I should use? At first I thought it was a linear regression because my outcome is continuous, but I'm not sure.
Yes, whenever you have a continuous variable that can take on any value within a range, ordinary linear regression, the lm function is a good place to start. If it can only be 1 or 0, you need logistic regression `glm(..., family = "binomial") to start.