Introduction to Stata 8 - (GRIPS

16. Do-file examples
Here follow short examples of do-files doing typical things. Find more examples in Take
good care of your data. All major work should be done with do-files rather than by entering
single commands because:
1. The do-file serves as documentation for what you did.
2. If you discover an error, you can easily correct the do-file and re-run it.
3. You are certain that commands are executed in the sequence intended.
Example 1 generates the first Stata version of the data, and example 2 generates a modified
version. I call both do-files vital in the sense that they document modifications to the data.
Such do-files are part of the documentation and they should be stored safely. Safe storage also
means safe retrieval, and they should have names telling what they do. My principle is this:
In example 1 gen.wine.do generates wine.dta. In example 2 gen.visit12a.do
generates visit12a.dta. This is different from example 3 where no new data are
generated, only output. This do-file is not vital in the same sense as example 1 and 2, and it
should not have the gen. prefix (the Never Cry Wolf principle).
As mentioned in section 3 I prefer to use NoteTab rather than the do-file editor for creating
do-files. The last command in a do-file must be terminated by a carriage return; otherwise
Stata cannot 'see' the command.
Example 1. gen.wine.do generates Stata data set wine.dta from ASCII file
/ / gen.wine.do creates wine.dta 13.5.2001
infix id 1-3 type 4 price 5-10 rating 11 ///
using c:\dokumenter\wines\wine.txt
// Add variable labels
label variable id "Identification number"
lab var type "Type of wine"
lab var price "Price per 75 cl bottle"
lab
var rating "Quality rating"
// Add value labels
label define type 1 "red" 2 "white" 3 "rosé" 4 "undetermined"
label values type type
lab def rating 1 "poor" 2 "acceptable" 3 "good" 4 "excellent"
lab
val rating rating
// Add data set label
label data "wine.dta created from wine.txt, 13.5.2001"
save c:\dokumenter\wines\wine.dta
Example 2. gen.visit12a.do generates visit12a.dta from visit12.dta
/ / gen.visit12a.do generates visit12a.dta with new variables.
use
c:\dokumenter\proj1\visit12.dta, clear
// Calculate hrqol: quality of life score.
egen hrqol=rsum(q1-q10)
label
variable hrqol "Quality of life score"
label
data "Visit12a.dta created by gen.visit12a.do, 02.01.2001"
save c:\dokumenter\proj1\visit12a.dta
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