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Re: st: Getting all independent vars from a set of reg equations


From   Nick Cox <njcoxstata@gmail.com>
To   statalist@hsphsun2.harvard.edu
Subject   Re: st: Getting all independent vars from a set of reg equations
Date   Mon, 27 Jun 2011 10:46:55 +0100

You did not show any of your code, but are presumably doing something like this

indeplist
local x = r(X)

when the latter line should be

indeplist
local x `r(X)'

See also

SJ-8-4  pr0045  . . . . . . . . Stata tip 70: Beware the evaluating equal sign
        . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  N. J. Cox
        Q4/08   SJ 8(4):586--587                                 (no commands)
        tip explaining the pitfall of losing content in a macro
        because of limits on the length of string expressions

I don't understand your second question. -drop y*- is perfectly legal.
When you say drop do you mean omit?

Nick

On Mon, Jun 27, 2011 at 10:08 AM, Narahari H.S. <naraharihs@yahoo.co.in> wrote:

> Thanks for the example code and the explanation. It works like a charm :).
>
> However, I have a large number of independent variables and their total no. of characters exceeds 244 - thus resulting in a truncation. How do I tackle this?
>
> Also, among the independent variables, I have dummy variables for years which are named with a "y" prefix (like y2000, y2005 etc.). Is there any way to drop these variables? (I was hoping for a -drop y*- command similar to -list uniq- but thats not available)
>
> Warm Regards
> Hari
>
>
>
> --- On Sun, 26/6/11, Maarten Buis <maartenlbuis@gmail.com> wrote:
>
> From: Maarten Buis <maartenlbuis@gmail.com>
> Subject: Re: st: Getting all independent vars from a set of reg equations
> To: statalist@hsphsun2.harvard.edu
> Date: Sunday, 26 June, 2011, 9:20 PM
>
> On Sat, Jun 25, 2011 at 3:45 PM, Narahari H.S. wrote:
>> I have to present a correlation matrix of all independent variables from a set of regression equations. I thought that if I could list (in one place) all the independent variables from all the equations, I could use them with the pwcorr command.
>
> You can get the independent variables of one regression model using
> -indeplist- (which is available form SSC). If you have multiple
> models, you need to know some tricks on how to deal with local macros
> in Stata. Below is an example with three models. First I stack all the
> names in one local macro `x', and than I drop the duplicate names
> using -local x: list uniq x-.
>
> *---------------- begin example -----------------------
> sysuse auto
>
> reg price mpg foreign
> indeplist
> local x = r(X)
>
> reg price mpg rep78 foreign
> indeplist
> local x "`x' `r(X)'"
>
> reg price mpg rep78 foreign gear_ratio
> indeplist
> local x "`x' `r(X)'"
>
> di "`x'"
>
> local x : list uniq x
> di "`x'"
>
> cor `x'
> *------------------ end example ----------------------
> (For more on examples I sent to the Statalist see:
> http://www.maartenbuis.nl/example_faq )
>

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