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# Re: st: loop code question

 From Nick Cox To statalist@hsphsun2.harvard.edu Subject Re: st: loop code question Date Sun, 12 Aug 2012 09:11:03 +0100

```1.

local list1 "A B C"
local list2 "a b c"
local n1 : word count `list1'
local n2 : word count `list2'
if `n1' != `n2' {
di as err "different counts"
}

forval i = 1/`n1' {
local first : word `i' of `list1'
local second : word `i' of `list2'
... `first' `second'

SJ-3-2  pr0009  . . . . . . . . . . . . . Speaking Stata:  Problems with lists
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  N. J. Cox
Q2/03   SJ 3(2):185--202                                 (no commands)
discusses ways of working through lists held in macros

2. No need for new variables

foreach y in 1994 1998 2005 {

.... if inlist(year, `=`y' - 1', `y', `=`y'+1')
}

On Sat, Aug 11, 2012 at 10:12 PM, Kaur, Dupinderjeet
<dxk110730@utdallas.edu> wrote:
> Dear All,
>
> I have two questions on using a loop to run regressions.
>
> 1)      I want to use pair of variables together when doing foreach, right now to do this I am doing a double loop and delegating combinations that I don't want.
> Here is the code, I need A a, B b, C c combination. How can I do this in a single loop?
>                 foreach x in A B C{
>                                 foreach y in a b c{
>                                 eststo: quietly reg dependent independent  `x' `y'
>                                 }
>                 }
> 2)      I have panel data with ID and year. I want to run event regressions. For example if my data is from 1990 to 2010, and I have identified events in 1994,
> 1998, 2005 then I want to run three regressions capturing 2 years data on both sides of the event year. Can I do a categorical variable that differentiates
> these events and then do a loop for regression, I am not sure how to do this exactly.
>
> I am a second year PhD student and new to Stata, so any guidance on these questions would be greatly appreciated.
>
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```