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Re: st: Test for statistical significance
From
Austin Nichols <[email protected]>
To
[email protected]
Subject
Re: st: Test for statistical significance
Date
Tue, 31 Aug 2010 10:50:24 -0400
Cornelius Nattey <[email protected]>:
Regress manganese blood levels on a dummy for month equal to November,
clustering by person (or higher level if using clustered survey data,
or if there is other clustering suspected). You might want to use
-glm- with a log link for your regression, since manganese blood
levels must be nonnegative, especially if they exhibit right skew.
The easy interpretation in the latter regression would be in terms of
a percentage difference, rather than a difference in levels.
webuse nhanes2, clear
egen c=group(strata psu)
ren female nov
qui reg zinc nov [pw=finalwgt], cl(c)
loc d=cond(sign(_b[nov])==1,"higher","lower")
di "`: var lab zinc' is " abs(_b[nov]) " `d' in November"
qui glm zinc nov [pw=finalwgt], link(log) cl(c)
di "`: var lab zinc' is " abs(exp(_b[nov])-1) "% `d' in November"
nlcom exp(_b[nov])-1
On Tue, Aug 31, 2010 at 10:24 AM, Cornelius Nattey
<[email protected]> wrote:
> Dear All,
> I have two datasets of manganese blood levels taken in August and
> November 2005. They were from the same community but mainly different
> people in the community. There may have been some repeats but I do not
> know how many if there were any. I have treated them as independent and
> not paired tests.
>
> What test should be applied to see if there is a statistically sig
> difference? Is there a difference?
>
> Thanks very much
> Cornelius
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