* do-file for Supplementary Exercises 7.102 and 7.103 of IPS7e
version 18 /* works also with versions 13-17 */

import delimited "R:\Chapter 7\ex07_102.csv", clear
rename r change
bysort group: stem change 
bysort group: summarize change, detail
bysort group: swilk change
bysort group: ci change
ttest change, by(group) unequal