6. What effect does adding covariates have on your estimate of the treatment effect? What does this tell you about the relationship between the covariates and being assigned to the treatment group? 7. Will comparing the voting rate of the treatment and control groups generate an unbi- ased estimate of the causal effect of getting assigned to get an encouraging call on the probability of voting? Why or why not? Explain. 8. Please attach all of the code you wrote to generate your results