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Data:
      id     m1     m2     m3
     106   22.2   30.6   13.9
     111   26.4   32.2   14.6
     119   23.6   28.9   26.7
     122   27.4   38.0   28.9
     130   17.5   24.5   41.4
     131   18.4   21.5   20.2
     133   28.1   28.1   22.3
     135   33.5   38.5   29.9
     140   18.9   25.7   15.1
     144   21.2   28.3   37.0
     149   18.8   25.6   15.5
     152   22.4   31.5   28.5
     153   21.5   28.6   22.5
     158   27.9   37.6   37.2
     167   30.1   42.3   24.0
     168   28.5   36.9   32.4
     171   23.5   36.7   27.8
     176   24.6   24.5   25.8
     180   29.4   30.3   15.2
     188   23.2   24.6    9.1
     191   25.7   31.7   31.2
     192   20.1   19.7    8.2
     194   23.4   27.7    6.0

Thank you,
Ricardo

--- On Thu, 2/2/12, Ricardo Ovaldia <[email protected]> wrote:

> From: Ricardo Ovaldia <[email protected]>
> Subject: Re: st: repeated measures ANOVA to MANOVA - revisit
> To: [email protected]
> Date: Thursday, February 2, 2012, 8:18 AM
> Using the 23 observations below I get
> very different (and concerning) p-values when I use repeated
> measurements ANOVA and MANOVA.
> From MANOVA:
> . gen myconst=1
> . manova m1 m2 m3= myconst, nocons
>  <Output suppressed>
> . mat c = (1,0,-1\0,1,-1)
> . manovatest mycons, ytransform(c)
> <Output suppressed>
> . mat l r(stat)
> 
> r(stat)[4,6]
>         statistic     
>     F        df1   
>     df2     pvalue 
>     exact
>  Wilks  .23525472  34.132474     
>     2     
>    21  2.519e-07     
>     1
> Pillai  .76474528  34.132474     
>     2     
>    21  2.519e-07     
>     1
> Lawley  3.2507118  34.132474     
>     2     
>    21  2.519e-07     
>     1
>    Roy  3.2507118  34.132474 
>         2     
>    21  2.519e-07     
>     1
> 
> From repeated ANOVA:
> . drop myconst
> . reshape long m, i(id) j(method)
> <Output suppressed>
> 
> . anova m id  method, repeat( method)
> <Top of output suppressed>
> â?¦
> Between-subjects error term:  id
>                
>      Levels:  23   
>     (22 df)
>      Lowest b.s.e. variable:  id
> 
> Repeated variable: method
>                
>                
>           Huynh-Feldt epsilon 
>       =  0.6357
>                
>                
>           Greenhouse-Geisser
> epsilon =  0.6174
>                
>                
>           Box's conservative
> epsilon =  0.5000
> 
>                
>                
>             ------------ Prob
> > F ------------
>                
>   Source |     df   
>   F    Regular    H-F   
>   G-G      Box
>              
> -----------+----------------------------------------------------
>                
>   method |      2   
> 10.12   0.0002   0.0020   0.0022   0.0043
>                
> Residual |     44
>              
> ----------------------------------------------------------------
> 
> MANOVA reports a p-value of 2.519e-07, whereas the
> Huynh-Feldt p-value from ANOVA is 0.0022.
> Any idea why they are so different? Am I doing something
> wrong? 
> 
> Thank you,
> Ricardo
> 
> Data:
>       id     m1 
>    m2     m3
>  
>    106   22.2   30.6   13.9
>  
>    111   26.4   32.2   14.6
>  
>    119   23.6   28.9   26.7
>  
>    122   27.4   38.0   28.9
>  
>    130   17.5   24.5   41.4
>  
>    131   18.4   21.5   20.2
>  
>    133   28.1   28.1   22.3
>  
>    135   33.5   38.5   29.9
>  
>    140   18.9   25.7   15.1
>  
>    144   21.2   28.3   37.0
>  
>    149   18.8   25.6   15.5
>  
>    152   22.4   31.5   28.5
>  
>    153   21.5   28.6   22.5
>  
>    158   27.9   37.6   37.2
>  
>    167   30.1   42.3   24.0
>  
>    168   28.5   36.9   32.4
>  
>    171   23.5   36.7   27.8
>  
>    176   24.6   24.5   25.8
>  
>    180   29.4   30.3   15.2
>  
>    188   23.2   24.6 
>   9.1
>  
>    191   25.7   31.7   31.2
>  
>    192   20.1   19.7 
>   8.2
>  
>    194   23.4   27.7 
>   6.0
> 
> 
> 
> Ricardo Ovaldia, MS
> Statistician 
> Oklahoma City, OK
> 
> 
> --- On Wed, 2/1/12, Ricardo Ovaldia <[email protected]>
> wrote:
> 
> > From: Ricardo Ovaldia <[email protected]>
> > Subject: Re: st: repeated measures ANOVA to MANOVA
> > To: [email protected]
> > Date: Wednesday, February 1, 2012, 9:18 AM
> > Never mind. Thank you. I found the
> > answer on page 359 of the manual.
> > I am now concerned because the pvalue from MANOVA is so
> much
> > smaller than the Huynh-Feldt corrected p-value
> > 
> > Thank you again,
> > Ricardo
> > 
> > Ricardo Ovaldia, MS
> > Statistician 
> > Oklahoma City, OK
> > 
> > 
> > --- On Wed, 2/1/12, Ricardo Ovaldia <[email protected]>
> > wrote:
> > 
> > > From: Ricardo Ovaldia <[email protected]>
> > > Subject: st: repeated measures ANOVA to MANOVA
> > > To: "Statalist" <[email protected]>
> > > Date: Wednesday, February 1, 2012, 8:50 AM
> > > I have data on 23 patients that were
> > > evaluated using three competing medical methods.
> I
> > used
> > > repeated measures ANOVA and reported the
> Huynh-Feldt
> > > corrected p-value. A reviewer suggested that it
> would
> > be
> > > better to do a MANOVA. However, when I try
> this, 
> > Stata
> > > reports the error:
> > > 
> > > . manova m1 m2 m3=id
> > > matrix not positive definite
> > > insufficient residual degrees of freedom for this
> > > multivariate model
> > > 
> > > Any help will be appreciated.
> > > Ricardo
> > > 
> > > Here is the data:
> > > . cl id m1 m2 m3
> > > 
> > >            id 
> > >    m1     m2 
> > >    m3
> > >   1.     
> > > 106   22.2   30.6   13.9
> > >   2.     
> > > 111   26.4   32.2   14.6
> > >   3.     
> > > 119   23.6   28.9   26.7
> > >   4.     
> > > 122   27.4   38.0   28.9
> > >   5.     
> > > 130   17.5   24.5   41.4
> > >   6.     
> > > 131   18.4   21.5   20.2
> > >   7.     
> > > 133   28.1   28.1   22.3
> > >   8.     
> > > 135   33.5   38.5   29.9
> > >   9.     
> > > 140   18.9   25.7   15.1
> > >  10.     
> > > 144   21.2   28.3   37.0
> > >  11.     
> > > 149   18.8   25.6   15.5
> > >  12.     
> > > 152   22.4   31.5   28.5
> > >  13.     
> > > 153   21.5   28.6   22.5
> > >  14.     
> > > 158   27.9   37.6   37.2
> > >  15.     
> > > 167   30.1   42.3   24.0
> > >  16.     
> > > 168   28.5   36.9   32.4
> > >  17.     
> > > 171   23.5   36.7   27.8
> > >  18.     
> > > 176   24.6   24.5   25.8
> > >  19.     
> > > 180   29.4   30.3   15.2
> > >  20.     
> > > 188   23.2   24.6   
> > > 9.1
> > >  21.     
> > > 191   25.7   31.7   31.2
> > >  22.     
> > > 192   20.1   19.7   
> > > 8.2
> > >  23.     
> > > 194   23.4   27.7   
> > > 6.0
> > > 
> > > 
> > > Ricardo Ovaldia, MS
> > > Statistician 
> > > Oklahoma City, OK
> > > *
> > > *   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/
> > > 
> > 
> > *
> > *   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/
> > 
> 
> *
> *   For searches and help try:
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> 

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