Write a SAS program to use the data set (named world2) saved in Exercise 2.16, in a proc tabulate step to print a tabulation giving the sample size, sample mean, sample standard deviation, and the standard error of the mean of the variables popurban for subgroups of observations defined by the combination of values of Techgrp and Deathgrp.

The row analysis consists of combinations of Techgrp and Deathgrp, and the statistics for Popurban must appear on the columns. Print the sample size without decimals, the sample mean with four decimal places, and the other two statistics with two decimal places each. Also, use appropriate text strings to label all statistic keyword headings (e.g., print Standard Deviation for std).