The file educ.dta in the heteroscedastic data sets folder on the website contains international cross-section data on aggregate expenditure on education, EDUC, gross domestic product, GDP, and population, POP, for a sample of 38 countries in 1997. EDUC and GDP are measured in U.S. $ million and POP is measured in thousands. Download the data set, plot a scatter diagram of EDUC on GDP, and comment on whether the data set appears to be subject to heteroscedasticity. Sort the data set by GDP and perform a Goldfeld-Quandt test for heteroscedasticity, running regressions using the subsamples of 14 countries with the smallest and greatest GDP.