Suppose you have data on year of birth, but you want to group several years together, e.g. group 1950, 1951 and 1952 births together; 1953, 1954, and 1955 together, etc.
Below is some JavaScript code I wrote to generate the relevant Stata commands without much fuss. You only have to make minor adjustments: Enter the start year (e.g. 1950), the end year (e.g. 1955), and the interval length (e.g. 3 years).
[sourcecode language=”javascript”]
<html><body><script>
//*** Generate Stata Code to replace cohort groups *****
//*** Enda Hargaden, Summer 2010
//*** Just replace the following three variables and refresh the page
var start_year = 1881;
var end_year = 1990;
var interval = 5;
//*** You’re done. Or at least you should be.
var c;
var a;
var backup1 = start_year;
var backup2 = end_year;
a = end_year – start_year;
a = a/interval;
a = Math.ceil(a);
a=a+1;
document.write("gen cohort_group = 0 <br />");
for(i=1;i<a;i++)
{
c=start_year+interval;
document.write("replace cohort_group = " + i + " if cohort > " + (start_year-1) + " & cohort < " + c + "<br />");
start_year = start_year+interval;
}
start_year = backup1;
end_year = backup2
document.write("<br />recode cohort_group ");
document.write("( 0 = 0 \"Other\" ) ///<br />");
for(j=1;j<a;j++)
{
if(j<(a-1))
{
c=start_year+interval-1;
document.write("( " + j + " = " + j + " \"" + (start_year) + " – " + c + "\" ) ///<br />");
start_year=start_year+interval;
}
if(j==a-1)
{
c=start_year+interval-1;
document.write("( " + j + " = " + j + " \"" + (start_year) + " – " + c + "\" ), gen(cohort_clean)<br />la var cohort_clean \"Birth Cohort\"<br />");
start_year=start_year+interval;
}
}
</script></body></html>
[/sourcecode]
I wrote this with a five-year interval in mind so I cannot guarantee you won’t run into an integer problem with the last entry, etc. However, it should get you most of the way there. Enjoy!
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