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st: Offset variable


From   "Stephen A. Crowder" <scrowder@umc.edu>
To   "<statalist@hsphsun2.harvard.edu>" <statalist@hsphsun2.harvard.edu>
Subject   st: Offset variable
Date   Mon, 9 Dec 2013 03:53:36 +0000

I am developing an ordinal logistic regression model examining a factor with several levels on my dependent variable. That part is straight forward enough but I have a main independent variable that ide like to control for in the examination of all of the other independent variables. My question is would I need to make this an "offset variable" in my models? I've been looking through the literature and there's no clear answer available.

Sent from my iPhone

> On Dec 8, 2013, at 12:58 PM, "Nick Cox" <njcoxstata@gmail.com> wrote:
>
> Your code does not define any -O- before you call Mata. So, Mata
> doesn't know what you are referring to. You can't refer in advance to
> what doesn't yet exist.
>
> What I think you want to do is pass a string to be used as the name of
> the thing you want to create. That would be need to shown as such e.g.
> "O" and your Mata would need to expect a string scalar as argument.
>
> That said, your Mata code so far just creates a matrix in Mata. That
> does nothing in terms of anything in Stata. It appears that you have
> Stata objects and Mata objects, but they are not at all the same.
>
> You could back up and describe the precise problem you want to solve.
> It is not at all clear that you need Mata to do it.
>
> It's also a stretch at best and impossible at worst, for Mata to
> understand Stata's local macros.
>
> As above, there is no "MATA". It is "Mata".
>
> Nick
> njcoxstata@gmail.com
>
>
>> On 8 December 2013 18:31, Jason Park <loooooo.j8311@gmail.com> wrote:
>> Dear users,
>>
>> Thanks to one of the previous threads
>> (http://www.stata.com/statalist/archive/2011-01/msg00393.html), I've
>> come to understand that, in a do file, mata should be moved outside of
>> a loop to before the loop so that the loop can call it.
>> However, the thread only shows the case where input is a scalar.
>> Instead, I want the name of a matrix that mata returns as a result,
>> say O, to be the parameter of the mata function. As shown below, the
>> mata function I want my loops to call is a matrix presentation of some
>> detailed calculation of the outputs of VAR results.
>>
>> * beginning of the do file
>> clear all
>> mata
>> void foobar(O) {
>> L = ("aa"\"bb")
>> M = J(2, 1, .)
>> M[1,1] = `aa'
>> M[2,1] = `bb'
>> O = L,M
>> }
>> end
>>
>> foreach case in "date<=10" "date>10&date<=20" "date>20" {
>> ma drop aa
>> ma drop bb
>> local aa = 0
>> local bb = 0
>> forvalues i = 1/10
>> var a b if id == `i' & `case', lags(1/2)
>> ma drop B
>> ma B = e(b)
>> local aa = `aa' + B[1,1]
>> local bb = `bb'+ B[1,6]
>> mata foobar(O)
>> }
>> * end of the do file
>>
>> This code returns:
>> <istmt>:  3499  O not found
>> r(3499);
>>
>> Could anyone provide some tips?
>>
>> Thanks in advance,
>> J
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