Introduction to Econometrics 3rd Edition by James Stock, James Stock

تمرين 26

Data on fifth-grade test scores (reading and mathematics) for 420 school districts in California yield = 646.2 and standard deviation s Y = 19.5.
a. Construct a 95% confidence interval for the mean test score in the population.
b. When the districts were divided into districts with small classes ( 20 students per teacher) and large classes ( 20 students per teacher), the following results were found: Is there statistically significant evidence that the districts with smaller classes have higher average test scores Explain.