clear
sjlog using solution, replace

global datadir http://personalpages.manchester.ac.uk/staff/mark.lunt/stats
use $datadir/2_summarizing_data/data/htwt.dta

ttest nurseht, by(sex)
ttest bmi, by(sex)
sdtest bmi, by(sex)
ttest bmi, by(sex) unequal
sysuse bpwide
summarize bp*
gen bp_diff =  bp_after- bp_before
ttest bp_diff == 0
sampsi 0.25 0.4, power(0.9)
sampsi 0.25 0.4, power(0.9) r(0.5)
sampsi 0.25 0.4, n(100)
sampsi 15 17, sd1(5) sd2(6) power(.90)
sampsi 15 17, sd1(5) sd2(6) power(.95)
sampsi 15 17, sd1(5) sd2(6) n1(100) n2(200)
sampsi 15 17, sd1(5) sd2(6) n1(100) n2(280)
sampsi 15 17, sd1(5) sd2(6) n1(100) n2(275)
sampsi 15 17, sd1(5) sd2(6) n1(100) n2(277)
sampsi 15 17, sd1(5) sd2(6) n1(100) n2(276)

sjlog close, replace