Notice: On April 23, 2014, Statalist moved from an email list to a forum, based at statalist.org.
[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: st: means compairison with weights and unequal variance
From
Nick Cox <[email protected]>
To
[email protected]
Subject
Re: st: means compairison with weights and unequal variance
Date
Mon, 21 Nov 2011 09:09:48 +0000
The syntax ` ' only de-references local macro names. Once you change
the syntax as you did, the --ttesti- call reduces to
ttesti, unequal
which makes no sense. There is no reason to change it anyway.
Nick
On Mon, Nov 21, 2011 at 9:02 AM, David Ashcraft
<[email protected]> wrote:
> John,
>
> I am trying to implement the code but replacing local with gen. Why I am not getting the same result, if I use gen rather than local?
>
> David
>
>
> ----- Original Message -----
> From: John Luke Gallup <[email protected]>
> To: [email protected]
> Cc:
> Sent: Monday, November 21, 2011 8:40:40 AM
> Subject: Re: st: means compairison with weights and unequal variance
>
> Barbro,
>
> A simple alternative is to calculate the means and standard deviations for each group using -summarize- with weights, and then run -ttesti ..., unequal-:
>
> sysuse auto, clear
>
> sum mpg if foreign [aw=weight]
> local N1 = r(N)
> local av1 = r(mean)
> local sd1 = r(sd)
>
> sum mpg if !foreign [aw=weight]
> local N2 = r(N)
> local av2 = r(mean)
> local sd2 = r(sd)
>
> ttesti `N1' `av1' `sd1' `N2' `av2' `sd2', unequal
>
> John
>
> John Luke Gallup
> Department of Economics
> Portland State University
>
*
* For searches and help try:
* http://www.stata.com/help.cgi?search
* http://www.stata.com/support/statalist/faq
* http://www.ats.ucla.edu/stat/stata/