2. Use the Stata data set seatbelts. dta on the course web site for this problem. Traffic crashes are a leading cause of death for Americans between the ages of 5 and 32. Through various spending policies, the federal government has encouraged states to institute mandatory seat belt laws to reduce the number of fatalities and serious injuries. In this exercise, you will investigate how effective these laws are in increasing seat belt use and reducing fatalities. The data .set seatbelts. dta contains a panel of data from 50 U. S. states plus the District of Columbia for the years 1983-1997. a. Estimate the effect of seat belt use on fatalities by regressing FatalityRate on sb_usage, speed65, speed70, ba08, drinkage21, ln(income), and age. Does the estimated regression suggest that increased seat belt use reduces fatalities? Explain. b. Do the results change when you add state fixed effects? If so, provide an intuitive explanation for why the results changed. c. Do the results change when you add time fixed effects plus state fixed effects? d. Which regression specification – a, b, or c – is most reliable? Explain why. e. Do the results in c indicate whether the coefficient of sb_usage is large, small, or some other size? Explain what you mean by whatever term you use to characterize the size of the coefficient. How many lives would be saved if seat belt use increased from 52% to 90%?