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use http://www.ats.ucla.edu/stat/stata/library/depress, clear
reshape long dep, i(subj)
rename _j time
drop pre
twoway ///
(lowess dep time if group == 0, lcolor("66 113 174") lwidth(thick)) ///
(lowess dep time if group == 1, lcolor("255 55 33") lwidth(thick)), ///
title("Depression Scores Over Time") ///
ytitle("Depression scores", size(medsmall)) ///
xtitle("Time") ///
graphregion(color(white)) ///
legend(cols(2) ///
label(1 "Placebo") ///
label(2 "Estrogen"))
graph export "/Users/jburchell/octopress/source/figure/lowess_graph_stata.png", ///
replace width(350)
capture program drop model_decision
program model_decision
args outcome
xtmixed `outcome' time i.group || subj: , var mle
di _newline(1)
di "Step 1: Evaluate initial model." _newline(2) ///
"Look at the bottom of the output where it reads: 'LR test vs. linear regression...Prob >= chibar2 ='" _newline(1) ///
"Does 'Prob >= chibar2' have a value of < .05? " _newline(2) ///
"Enter a value below in the 'command' window (y/n)" _request(_answer1)
if ("`answer1'" == "y") {
xtmixed `outcome' time time_sq i.group || subj: , var mle
di _newline(2) ///
"Step 2: Now look at the row of the first table labelled 'time_sq'." _newline(1) ///
"Is this variable significant? " _newline(2) ///
"Enter a value below in the 'command' window (y/n)" _request(_answer2)
di _newline(2)
}
else if ("`answer1'" == "n") {
regress `outcome' time time_sq i.group, vce(cluster subj)
di _newline(2) ///
"Step 2: Now look at the row of the table labelled 'time_sq'." _newline(1) ///
"Is this variable significant? " _newline(2) ///
"Enter a value below in the 'command' window (y/n)" _request(_answer3)
di _newline(2)
}
if ("`answer2'" == "y") {
di _newline(2) ///
"The final model for `outcome' is below. " ///
"This is a random-intercepts multilevel model with a quadratic term."
di _newline(1)
xtmixed `outcome' time time_sq i.group || subj: , var mle
}
else if ("`answer2'" == "n") {
di _newline(2) ///
"The final model for `outcome' is below. " ///
"This is a random-intercepts multilevel model."
di _newline(1)
xtmixed `outcome' time i.group || subj: , var mle
}
if ("`answer3'" == "y") {
di _newline(2) ///
"The final model for `outcome' is below. " ///
"This is a linear regression with a quadratic term which has robust standard errors clustered by ID."
di _newline(1)
regress `outcome' time time_sq i.group, vce(cluster subj)
}
else if ("`answer3'" == "n") {
di _newline(2) ///
"The final model for `outcome' is below. " ///
"This is a linear regression which has robust standard errors clustered by ID."
di _newline(1)
regress `outcome' time time_sq i.group, vce(cluster subj)
}
end
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