Hello everyone, I am new to Stata and need your help.
I can run the following simple regression with the attached dataset:


clear all

import excel "xyz1.xlsx", firstrow case(lower) clear

gen lxa = ln(20+xa)
reg y lxa za

In the dataset, I have the following variables:
t y xa xb xd xf za zb zd zf


I would like to repeat the regression as follows:
gen lxb = ln(20+xb)
reg y lxb zb

......

gen lxd = ln(20+xd)
reg y lxd zd
......

gen lxf = ln(20+xf)
reg y lxf zf
......

How may I write a loop over 'a', 'b', 'd', 'f' to do the above task?

Thank you very much!!