program define tci
version 2.1
*! This is version 1.2   26 July 1991
* (mult. graphs added; re-wrote code for computing group means)
mac def _FN %S_FN
        mac def _varlist "req ex min(2)"
        mac def _if "opt"
        mac def _in "opt"
        parse "%_*"
        parse "%_varlist", parse(" ")
    qui ta %_2 %_if %_in, gen(_group)
    qui replace %_2=_group2
    drop _group*
         qui reg %_1 %_2
         mac def _diff=_b[%_2]
         mac def _m1=_b[_cons]
         mac def _df=_result(5)
         mac def _en=_result(1)
         emdef sdiff : se %_2
         emdef tdiff : t %_2
         emdef S2_t1 : invt .999 %_df

di ""
di "Following are confidence intervals for the difference:"
di _co(43) "Lower Limit" _sk(5) "Upper Limit"
di "The level(.999) confidence interval is:"/*
   */ _co(43) %9.4f %_diff-(%S2_t1*%sdiff) _co(59) %8.4f %_diff+(%S2_t1*%sdiff)
         emdef S2_t2 : invt .99 %_df
di "The level(.99) confidence interval is:"/*
   */ _co(43) %9.4f %_diff-(%S2_t2*%sdiff) _co(59) %8.4f %_diff+(%S2_t2*%sdiff)
         emdef S2_t3 : invt .95 %_df
di "The level(.95) confidence interval is:"/*
   */ _co(43) %9.4f %_diff-(%S2_t3*%sdiff) _co(59) %8.4f %_diff+(%S2_t3*%sdiff)
         emdef S2_t4 : invt .90 %_df
di "The level(.90) confidence interval is:"/*
   */ _co(43) %9.4f %_diff-(%S2_t4*%sdiff) _co(59) %8.4f %_diff+(%S2_t4*%sdiff)
         emdef S2_t5 : invt .80 %_df
di "The level(.80) confidence interval is:"/*
   */ _co(43) %9.4f %_diff-(%S2_t5*%sdiff) _co(59) %8.4f %_diff+(%S2_t5*%sdiff)
         emdef S2_t6 : invt .65 %_df
di "The level(.65) confidence interval is:"/*
   */ _co(43) %9.4f %_diff-(%S2_t6*%sdiff) _co(59) %8.4f %_diff+(%S2_t6*%sdiff)
         emdef S2_t7 : invt .50 %_df
di "The level(.50) confidence interval is:"/*
   */ _co(43) %9.4f %_diff-(%S2_t7*%sdiff) _co(59) %8.4f %_diff+(%S2_t7*%sdiff)
di ""
di "mean for first group is "%9.4f %_m1 /*
 */ _sk(4) "mean for second group is "%9.4f %_m1+%_diff
di ""
di "The difference is: "%9.4f in gr %_diff _sk(3) in ye /*
   */"t: "%8.4f in wh %tdiff _sk(2) in ye "and p-value is "/*
    */ %6.4f in gr tprob(%_df,%tdiff) _sk(1) in ye "(N=" %_en ")"
di ""
if _N<8 { set obs 8 }
capture {
gen _lo=.
gen _hi=.
gen index=.
replace index=.50 if _n==2
replace index=.65 if _n==3
replace index=.80 if _n==4
replace index=.90 if _n==5
replace index=.95 if _n==6
replace index=.99 if _n==7
replace index=.999 if _n==8
replace _lo=%_diff-(%S2_t7*%sdiff) if _n==2
replace _lo=%_diff-(%S2_t6*%sdiff) if _n==3
replace _lo=%_diff-(%S2_t5*%sdiff) if _n==4
replace _lo=%_diff-(%S2_t4*%sdiff) if _n==5
replace _lo=%_diff-(%S2_t3*%sdiff) if _n==6
replace _lo=%_diff-(%S2_t2*%sdiff) if _n==7
replace _lo=%_diff-(%S2_t1*%sdiff) if _n==8
replace _lo=%_diff if _n==1
replace _hi=%_diff if _n==1
replace _hi=%_diff+(%S2_t1*%sdiff) if _n==8
replace _hi=%_diff+(%S2_t2*%sdiff) if _n==7
replace _hi=%_diff+(%S2_t3*%sdiff) if _n==6
replace _hi=%_diff+(%S2_t4*%sdiff) if _n==5
replace _hi=%_diff+(%S2_t5*%sdiff) if _n==4
replace _hi=%_diff+(%S2_t6*%sdiff) if _n==3
replace _hi=%_diff+(%S2_t7*%sdiff) if _n==2
}
    mac def TCI=%TCI+1
graph _lo _hi index, c(II) yline(%_diff,0) rlab(%_diff,0) ylab(%_diff,0) /*
 */ s(ii) xlab(.999,.95,.90,.80,.65,.50) tlab(.99,.95,.90,.50) sav(%TCI) /*
 */ b1("Confidence Level") l1("Size of Difference") b2(" ") /*
 */ xtick(.999,.99,.95,.90,.80,.65,.50) ttick(.999,.99,.95,.90,.80,.65,.50)
drop _lo _hi index
use %_FN, replace
end