*! version 1.0.0 10 March 1997 STB-36 ip16
program define ptransdb
        version 5.0

        local varlist opt
        parse "`*'"
        global DB_var "`varlist'"

        global DB_one "Data variable:"
        window control static          DB_one  10 10 50 9
        global DB_data " "
        window control ssimple         DB_var  10 20 50 50 DB_data

        global DB_two "Time variable:"
        window control static          DB_two  70 10 50 9
        global DB_time " "
        window control ssimple         DB_var  70 20 50 50 DB_time

        global DB_l "lambda:"
        window control static          DB_l    70 80  50 9
        global DB_lams "0 .05 .10 .15 .20 .25 .30 .35 .40 .45 .50 .55 .60"
        global DB_lams "$DB_lams .65 .70 .75 .80 .85 .90 .95 1"
        global DB_lam "1"
        window control ssimple         DB_lams 70 90 50 60 DB_lam

        window control button "lambda"      5 100 40 10 DB_lc 
        window control button "lambda+"     5 115 40 10 DB_lp 
        window control button "lambda-"     5 130 40 10 DB_lm
        window control button "exit"        5 145 40 10 DB_ex

        global DB_lc  "bcdr 0" 
        global DB_lp  "bcdr 1"
        global DB_lm  "bcdr -1"

        global DB_ex "exit 3000"

        wdlg "Time series power transform" 10 10 140 170

end

program define bcdr
        version 5.0

        local arg `1'

        tempvar x t

        gen `x'=$DB_data
        gen `t'=$DB_time

        if `arg' == -1 {global DB_lam=max(0,$DB_lam-.025)}
        if `arg' ==  1 {global DB_lam=min(1,$DB_lam+.025)}

        if $DB_lam==0 {replace `x'=log(`x')}
        else {         replace `x'=`x'^$DB_lam}

        sum `x'
        replace `x'=(`x'-_result(5))/(_result(6)-_result(5))   


        tempvar cs sn yhat
        gen `cs'=cos(2*_pi*_n/12)
        gen `sn'=sin(2*_pi*_n/12)
        regress `x' `t' `cs' `sn'
        local s2: display %9.4f _result(9)                


        local lam: display %5.3f $DB_lam
        label var `x' " "
        label var `t' " "
        graph `x' `t', xlab ylab c(l) t1("Power transform (lambda=`lam', RMSE=`s2')")
        
        drop `x' `t'
end