Re: st: looping twice over same variables without repeating results

[Nick Cox <njcoxstata@gmail.com>]

OK, but that bites the other way. You can easy get half but how are
you going to avoid choices of response (outcome, regressand,
criterion, dependent variable) that are arbitrary; there is an
asymmetry to -regress y x- and -regress x y-.

Any way, as a matter of Stata technique, this appears to be what you
are asking for:

sysuse auto, clear
unab varlist : price-foreign
local nv : word count `varlist'
local nvm1 = `nv' - 1
tokenize "`varlist'"

forval i = 1/`nvm1' {
	local J = `i' + 1
	forval j = `J'/`nv' {
		di "``i'' ``j''"
		regress ``i'' ``j''
	}
}

On Fri, May 18, 2012 at 11:31 AM, Beatriz Rodriguez Prado
<bprado@eco.uva.es> wrote:
> Thank you Nick.
> The other question you raise is my problem. Sorry it was not clear.
> I do not want to regress y on x and x on y. I just want one of two
> regressions.
>
> Beatriz
>
>
> El 18/05/2012 12:03, Nick Cox escribió:
>>
>> Your question raises another which is whether you want the regression
>> of y on x _and_ the regression of x on y.
>>
>> foreach x of local varlist {
>>         foreach y of local varlist {
>>                  if "`x'" != "`y'" regress `y' `x'
>>         }
>> }
>>
>> is a safer and better way to avoid -regress-ing a variable on itself
>> but it will produce all the other p (p - 1) regressions for p
>> variables.
>>
>> Nick
>>
>> On Fri, May 18, 2012 at 10:52 AM, Beatriz Rodriguez Prado
>> <bprado@eco.uva.es>  wrote:
>>
>>> I have 3 variables named pmm_and pmm_ext pmm_es and I want to make simple
>>> regressions of each pair of variables.
>>> I have writen this code
>>>
>>> foreach x in and ext es {
>>>    foreach y in and ext es{
>>>        if pmm_`x'!=pmm_`y' {
>>>        regres pmm_`x' pmm_`y'
>>>        }
>>>    }
>>> }
>>>
>>> How could avoid to run repeated regressions?
>>> In fact I have 50 variables and have to run regressions, test some
>>> hyphotesis and make graphs and the output of the loop is unnecesary big.
>>

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