RE: st: RE: R�p. : st: RE: formatting and exporting ttest results

["Akihito Tokuhara" <akitoku4@hotmail.com>]

Dear Ina,

As others have given advice on commands for t-test, my reply here is about 
how to export or
write out to a text *.txt file with user-made formats suitable for different 
objective, which I don't
know if that is what Ina's question is about. You can use the command -- 
file write -- like this:

-----------------
file open anyname using myresult.txt, write text append/replace;
file write anyname  _newline  _col(18)  " <**>> stuffs here <<**> "   
_newline;
file write anyname  _newline  _col(4)  " ** others ** "   _newline;
file close anyname;
----------------

The command -- file write -- is like -- display --, and you have to test the 
output text file until you
get the format you want. I often have to use this to get the format I need 
for converting to
different forms of tables. Sometimes you may need to create temporary 
variables to save the
results for the writing out to text file. I am not sure if this is what Ina 
asked about. HTMH.

Akihito

-------------------------

> From: "Newson, Roger B" <r.newson@imperial.ac.uk>
> Reply-To: statalist@hsphsun2.harvard.edu
> To: <statalist@hsphsun2.harvard.edu>
> Subject: st: RE: R�p. : st: RE: formatting and exporting ttest results
> Date: Wed, 12 Apr 2006 16:36:11 +0100
>
> Another possibility for saving t-test results (although not a short one) is 
> to use -regress- together with -parmby- and -metaparm-. This has the 
> advantage that -metaparm- uses the Satterthwaite corrected degrees of 
> freedom, so the confidence limits will be robust to heteroskedasticity 
> between the two groups compared.
>
> For instance:
>
> sysuse auto, clear
> parmby "regress weight, robust", by(foreign) norestore
> tempfile tf1
> metaparm [iweight=!foreign-foreign], saving(`tf1', replace)
> append using `tf1'
> list
>
> will produce and display a dataset in memory (overwriting the original 
> -auto- data), with 1 observation for each of 3 parameters (mean US car 
> weight, mean non-US car weight, and their difference). These results will 
> be essentially the same as those produced by the shorter program
>
> sysuse auto, clear
> ttest weight, by(foreign) unequal
>
> However, the results produced by -parmby- and -metaparm- can be tabulated 
> and/or plotted as the user desires. This is an example of the resultsset 
> approach to plotting and tabulating results, and more references on this 
> can be found in the online help for the -parmest- package (which includes 
> -parmby-). Both -parmby- and -metaparm- can be downloaded from SSC using 
> the -ssc- command in Stata.
>
> I hope this helps.
>
> Roger
>
>
> Roger Newson
> Lecturer in Medical Statistics
> POSTAL ADDRESS:
> Respiratory Epidemiology and Public Health Group
> National Heart and Lung Institute at Imperial College London
> St Mary's Campus
> Norfolk Place
> London W2 1PG
> STREET ADDRESS:
> Respiratory Epidemiology and Public Health Group
> National Heart and Lung Institute at Imperial College London
> 47 Praed Street
> Paddington
> London W1 1NR
> TELEPHONE: (+44) 020 7594 0939
> FAX: (+44) 020 7594 0942
> EMAIL: r.newson@imperial.ac.uk
> WEBSITE: http://www.imperial.ac.uk/nhli/r.newson/
> Opinions expressed are those of the author, not of the institution.
>
>
> -----Original Message-----
> From: owner-statalist@hsphsun2.harvard.edu 
> [mailto:owner-statalist@hsphsun2.harvard.edu] On Behalf Of Herve STOLOWY
> Sent: 12 April 2006 16:02
> To: statalist@hsphsun2.harvard.edu
> Subject: R�p. : st: RE: formatting and exporting ttest results
>
> Dear Ina:
>
> Sorry, I did not see your first posting. I just discovered Nick's reply. 
> Some time ago, I raised the same issue and received several replies which 
> helped to find a solution. But this solution, as Nick said, is not a "short 
> answer".
>
> If you make a ttest with a groupvar, you can use -statsmat- and 
> -makematrix- (downloadable from ssc)(with -ttest-) followed by -mat2txt- 
> (downloadable from ssc) to get a .txt file.
>
> Here is an example I used for one research project:
>
> statsmat size1, s(N mean sd) by(format_bs) mat(mat1)
> makematrix mat2, from(r(t) r(p)) label : ttest size1, by(format_bs)
> matrix mat3=mat2' //Transposition of the matrix
> matrix mat4 = mat1, mat3 // Grouping of the two matrices
> matrix colnames mat4 = "Number of observations" Mean "Standard deviation" 
> "Student t-test"
> mat2txt, matrix(mat4) saving(univariate_bs) replace
>
> If you want to compare two variables with a ttest, here is another example 
> and solution:
>
> makematrix T5A1, from(r(N) r(mean) r(sd) r(min) r(p50) r(max)) label : 
> univar MAPE_direct_scal MAPE_indirect_scal if outlier_cfo_scal!=1 
> &outlier_MAPE!=1
> ttest MAPE_direct_scal = MAPE_indirect_scal if outlier_cfo_scal!=1 
> &outlier_MAPE!=1
> mat T5A2 = r(p) \ r(t)
> mat T5A3 = T5A1, T5A2
> matrix colnames T5A3 = N "Mean" "Std Dev" "Min" "Median"  "Max" "T/p-value"
> mat2txt, matrix(T5A3) saving(stat_MAPE_table5A)  replace
>
> The syntax might not the most effective but I know these commands work.
>
> I hope this helps.
>
> Best regards
>
> Herv� Stolowy
> ***********************************************************
> Professeur/Professor
> Coordinateur du D�partement/Head of Department
> HEC Paris
> D�partement Comptabilit� Contr�le de gestion / Dept of Accounting and 
> Management Control
> 1, rue de la Liberation
> 78351 - Jouy-en-Josas
> France
> Tel: +33 1 39 67 94 42 - Fax: +33 1 39 67 70 86
> stolowy@hec.fr
> http://studies.hec.fr/web/stolowy
> >>> n.j.cox@durham.ac.uk 12/04/06 13:50 >>>
> The short answer is: Evidently not.
>
> However, as a t-test comparing two group means
> is really a regression in disguise, you
> should be able to use your favourite post-regression
> program for this purpose.
>
> Nick
> n.j.cox@durham.ac.uk
>
> Ina Ganguli
>
> > I was wondering whether there is a command (like -outreg-) I can use
> > to format and export multiple -ttest- results to a .txt file for
> > easier conversion to tables?
> >
> > I would like to have results in the following format:
> >
> >                     Group1     Group2     Difference
> > variable1       mean       mean        mean*
> >                       (se)          (se)          (se)
> > variable2       mean       mean        mean*
> >                       (se)          (se)          (se)
> > etc.
> >
> > I've seen references to commands that may perhaps be what I need
> > (-tabexport-, -parmby-?), but I wanted to check whether there is a
> > program/command out there that would work well for this.
>
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