st: RE: Easy Question: pvalues for means for groups

[Joe Canner <jcanner1@jhmi.edu>]

Ben,

While you will have to do some of the formatting yourself, you could use -ttest price==0- and then grab r(mu_1), r(se), r(t), r(p), etc.

Of course, if you want to stratify by type, you will have to loop through the levels of type and get the values you want each time through the loop.  As per a recent thread, -bys type:- will probably not work, because you can't get the values for each level.

Regards,
Joe Canner
Johns Hopkins University School of Medicine

-----Original Message-----
From: owner-statalist@hsphsun2.harvard.edu [mailto:owner-statalist@hsphsun2.harvard.edu] On Behalf Of Ben Hoen
Sent: Friday, September 06, 2013 1:16 PM
To: statalist@hsphsun2.harvard.edu
Subject: st: Easy Question: pvalues for means for groups

Hi all,

I am trying to find a simple way to output a set of tests (e.g., p-values) of means (i.e., are they different from 0) across groups (there are 6 of them).  Ideally .tabstat, which outputs a mean and a se would also produce a pvalue (in this case, the probability that the mean is different from zero) because that tabular output is preferable.  

**** example ****

sysuse auto, clear
g type=round((runiform()*5)+1)
tabstat price, stat(mean sem) by(type)  //in addition to these two stats it would, ideally, produce a p-value

***** end *******

I can use .reg, of course, but I then I need to convert the coef using the constant.

**** example ****

sysuse auto, clear
g type=round((runiform()*5)+1)
reg price ib1.type  

***** end *******

I suspect I am missing something very obvious, but I have not been able to figure it out.  Anyone able to quickly send me on my way?

Thanks, in advance,

Ben


Ben Hoen
Staff Research Associate
Lawrence Berkeley National Laboratory
Office: 845-758-1896
Cell: 718-812-7589
bhoen@lbl.gov
http://emp.lbl.gov/staff/ben-hoen

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