Use APPLE.RAW to verify some of the claims made in Section 6.3.
(i) Run the regression ecolbs on ecoprc, regprc and report the results in the usual form, including the R-squared and adjusted R-squared. Interpret the coefficients on the price variables and comment on their signs and magnitudes.
(ii) Are the price variables statistically significant? Report the p-values for the individual t tests.
(iii) What is the range of fitted values for ecolbs? What fraction of the sample reports ecolbs = 0? Comment.
(iv) Do you think the price variables together do a good job of explaining variation in ecolbs? Explain.
(v) Add the variables famine, hhsize (household size), educ, and age to the regression from part (i). Find the p-value for their joint significance. What do you conclude?