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. 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,Â
> 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
> >
> > Â Â Â Â Â Â Â idÂ
> > Â Â Â m1Â Â Â Â m2Â
> > Â Â Â m3
> >  1.  Â
> > 106Â Â Â 22.2Â Â Â 30.6Â Â Â 13.9
> >  2.  Â
> > 111Â Â Â 26.4Â Â Â 32.2Â Â Â 14.6
> >  3.  Â
> > 119Â Â Â 23.6Â Â Â 28.9Â Â Â 26.7
> >  4.  Â
> > 122Â Â Â 27.4Â Â Â 38.0Â Â Â 28.9
> >  5.  Â
> > 130Â Â Â 17.5Â Â Â 24.5Â Â Â 41.4
> >  6.  Â
> > 131Â Â Â 18.4Â Â Â 21.5Â Â Â 20.2
> >  7.  Â
> > 133Â Â Â 28.1Â Â Â 28.1Â Â Â 22.3
> >  8.  Â
> > 135Â Â Â 33.5Â Â Â 38.5Â Â Â 29.9
> >  9.  Â
> > 140Â Â Â 18.9Â Â Â 25.7Â Â Â 15.1
> > 10.  Â
> > 144Â Â Â 21.2Â Â Â 28.3Â Â Â 37.0
> > 11.  Â
> > 149Â Â Â 18.8Â Â Â 25.6Â Â Â 15.5
> > 12.  Â
> > 152Â Â Â 22.4Â Â Â 31.5Â Â Â 28.5
> > 13.  Â
> > 153Â Â Â 21.5Â Â Â 28.6Â Â Â 22.5
> > 14.  Â
> > 158Â Â Â 27.9Â Â Â 37.6Â Â Â 37.2
> > 15.  Â
> > 167Â Â Â 30.1Â Â Â 42.3Â Â Â 24.0
> > 16.  Â
> > 168Â Â Â 28.5Â Â Â 36.9Â Â Â 32.4
> > 17.  Â
> > 171Â Â Â 23.5Â Â Â 36.7Â Â Â 27.8
> > 18.  Â
> > 176Â Â Â 24.6Â Â Â 24.5Â Â Â 25.8
> > 19.  Â
> > 180Â Â Â 29.4Â Â Â 30.3Â Â Â 15.2
> > 20.  Â
> > 188Â Â Â 23.2Â Â Â 24.6Â Â
> > 9.1
> > 21.  Â
> > 191Â Â Â 25.7Â Â Â 31.7Â Â Â 31.2
> > 22.  Â
> > 192Â Â Â 20.1Â Â Â 19.7Â Â
> > 8.2
> > 23.  Â
> > 194Â Â Â 23.4Â Â Â 27.7Â Â
> > 6.0
> >
> >
> > Ricardo Ovaldia, MS
> > Statistician
> > Oklahoma City, OK
> > *
> > *Â Â Â For searches and help try:
> > *Â Â Â http://www.stata.com/help.cgi?search
> > *Â Â Â http://www.stata.com/support/statalist/faq
> > *Â Â Â http://www.ats.ucla.edu/stat/stata/
> >
>
> *
> *Â Â Â For searches and help try:
> *Â Â Â http://www.stata.com/help.cgi?search
> *Â Â Â http://www.stata.com/support/statalist/faq
> *Â Â Â http://www.ats.ucla.edu/stat/stata/
>
*
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