* do-file for Exercise 26.33 of PSLS 3e
version 15 /* works also with versions 13-14 */

import delimited "R:\Chapter 26\ex26_033.csv"
rename ventilation vent
encode acclimation, gen(acclim)
rename temperature temp
table temp acclim, contents( mean vent sd vent)

anova vent temp acclim temp#acclim
predict pred, xb
sort acclim temp
overlay pred temp, by(acclim) c(l)

predict stdres, rstandard
scatter stdres pred
qnorm stdres

generate rvent=sqrt(vent)
anova rvent temp acclim temp#acclim
predict rpred, xb
overlay rpred temp, by(acclim) c(l)
predict rstdres, rstandard
scatter rstdres rpred
qnorm rstdres
pwcompare i.temp#i.acclim
* manual calculation of LSD-values
display invttail(170,.025)*1.44441*sqrt(2/18)
display invttail(170,.025/25)*1.44441*sqrt(2/18)