Saturday, February 25, 2006

st: RE: Looping through a variable list

Assuming that you are using Stata 9.1 (Statalist convention) or even Stata >= 7 this can be done much more simply.

foreach v in A B C D { local x "`x' `v'" regress y `x' }

With strings always copy if you can, and evaluate only if you must.

Thus

local x

is better style than

local x = ""

In the example above I assumed no prior use of x.

Nick n.j.cox@durham.ac.uk

craig@pharmacy.arizona.edu > I would like to loop my estimations through an increasing number of > variables, but I am having difficulty undating my varlist. > > For example, suppose there were four variable (A B C D) and I wish to > estimate x on y where x is one of the four sets: "A", "A B", > "A B C", and > "A B C D". > > tokenize "A B C D" > local i = 1 > local x = "" > while i<=4 { > local x = `x'+``i'' > regress y `x' > local i=`i'+1 > } > > This program does not work because I can not get x to update.

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