Re: st: Repeated measures

[David Airey <david.airey@vanderbilt.edu>]

.

I think measurements nested in wire is the residual in the model

anova force wiretype / wireno|wiretype /

-Dave


On Mar 14, 2009, at 11:26 AM, TA Stat wrote:

> I think it is measurements nested in specimen nested in wiretype.
> Your main objective is to identify whether variation among wiretype is
> significant or not.  Right?
>
> Pete
>
> On Sat, Mar 14, 2009 at 11:12 PM, David Airey
> <david.airey@vanderbilt.edu> wrote:
> > .
> >
> > I was confused by your data layout.
> >
> > Your data are really just 3 columns wide:
> >
> > WireType WireNo Force
> >
> > where wiretype and wireno are replicated 5 times,
> >
> > So
> >
> > anova force wiretype / wireno|wiretype /
> >
> > is fine, or the equivalent xtmixed...
> >
> > -Dave
> >
> > On Mar 14, 2009, at 3:16 AM, Nikolaos Pandis wrote:
> >
> > > Dear Statalisters,
> > >
> > > I have the following dataset (except I have it in long format-one
> > > measurement per row) :
> > >
> > > WireType        WireNo  Trial           Force
> > >
> > > A       A1      1,2,3,4,5             5 measurements-1 per trial
> > > A       A2      1,2,3,4,5             5 measurements-1 per trial
> > > A       A3      1,2,3,4,5             5 measurements-1 per trial
> > > A       A4      1,2,3,4,5             5 measurements-1 per trial
> > > A       A5      1,2,3,4,5             5 measurements-1 per trial
> > >
> > > B       B1      1,2,3,4,5             5 measurements-1 per trial
> > > B       B2      1,2,3,4,5             5 measurements-1 per trial
> > > B       B3      1,2,3,4,5             5 measurements-1 per trial
> > > B       B4      1,2,3,4,5             5 measurements-1 per trial
> > > B       B5      1,2,3,4,5             5 measurements-1 per trial
> > >
> > >
> > > C       C1      1,2,3,4,5             5 measurements-1 per trial
> > > C       C2      1,2,3,4,5             5 measurements-1 per trial
> > > C       C3      1,2,3,4,5             5 measurements-1 per trial
> > > C       C4      1,2,3,4,5             5 measurements-1 per trial
> > > C       C5      1,2,3,4,5             5 measurements-1 per trial
> > >
> > > D       D1      1,2,3,4,5             5 measurements-1 per trial
> > > D       D2      1,2,3,4,5             5 measurements-1 per trial
> > > D       D3      1,2,3,4,5             5 measurements-1 per trial
> > > D       D4      1,2,3,4,5             5 measurements-1 per trial
> > > D       D5      1,2,3,4,5             5 measurements-1 per trial
> > >
> > > I am testing the forces generated by 4 different wiretypes to see  
> > > if there
> > > are significant differences.
> > > For each wiretype (categorical A B C D) I am using 5 specimens
> > > (A1-5,..D1-5) and for each specimen I am repeating the measurement  
> > > 5 times.
> > > The outcome is force and it is a continuous variable.
> > >
> > > This looks like a repeated measures with each trial nested in the  
> > > WireNo
> > > and the WireNo nested inside WireType?
> > >
> > > I was trying to use the xtgee command but I was not sure how to  
> > > construct
> > > it:
> > > xi:xtreg force i.xxxxx i.yyyyyy, i(zzzzz) ?
> > >
> > > Any help would be appreciated.
> > >
> > > Thank you very much,
> > >
> > > Nikolaos
> > >
> > >
> > >
> > >
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