* do-file for Supplementary Exercises 7.91 and 7.93 of IPS7e
version 17 /* works also with versions 13-16 */

* Exercise 7.91
ttesti 10 -3.67 33.89  20 -23.17 50.74, unequal
ttesti 10 -3.67 33.89  20 -23.17 50.74, unequal welch
* almost identical results, both methods are ok

* Exercise 7.93
ttesti 10 -3.67 33.89  20 -23.17 50.74
* note that the Stata default is equal variances -
* considering the recommendations in the textbooks a strange choice