conditional bysort

[sylvan chin]

Hi there,
I have a simple question on the function of bysort.
I know that we can use it to generate sum/mean by group. Usually bysort classify groups by a variable, yet can we make it a range?
For instance if I have data on people's calorie intake by age, gender and race. How can I know the group statistics on the group (female, white, age from 20-30)?

Thank you!

[ben earnhart]

I might be wrong, but I am fairly certain you need to create a variable to capture the range, then bysort by that. Which should be easy enough. Female and race don't need a recode, so all you'd need to do is a few lines (or even a single line with -recode-) to categorize age.

[sylvan chin]

Good idea! Thank you Ben!

[Nick Cox]

Ben is absolutely correct that you need to have a variable created to do this.

I'd add that recode is not the only way to categorise finely reported variables. For example,

 
gen age2 = 10 * floor(age/10)

creates 10 year wide bins.