[R] error MANOVA in R

[Gian Maria Niccolò Benucci]

Hi Peter,
Thank you so much for your tips. Have a nice Easter.
Gian

Il giovedì 2 aprile 2015, peter dalgaard <pdalgd at gmail.com> ha scritto:

>
> > On 30 Mar 2015, at 17:11 , Gian Maria Niccolò Benucci <
> gian.benucci at gmail.com <javascript:;>> wrote:
> >
> > Dear R-usrs,
> >
> > I am trying to perform a MANOVA on a data frame with 31 columns about
> soil
> > parameters and 1 column containing the explanatory variable (Fraction)
> that
> > have three levels.
> > my code is the following:
> >
> > datam <- read.table("data_manova2.csv", header=T, sep=",")
> > names(datam)
> >
> > manova_fraction2 <- manova(cbind(pH, AWC, WEOC, WEN, C.mic, CO2.C, Ca,
> Mg,
> > K, Na, sol.exch.Fe, easily.reducible.Fe, amourphou.Fe.oxide...Fe.OM,
> > crystalline.Fe.oxides, TN, TOC, NH4.N, NO3.N, N.org, organic.P,
> avaiable.P,
> > Total.PLFA, Tot.Bat, Gram., Gram..1, Funghi, AMF, protozoa, actinomiceti,
> > non.specifici) ~ as.factor(Fraction), data= datam)
> >
> > summary(manova_fraction2)
> >
> > when I did the summary I got this error
> >
> >> summary(manova_fraction2)
> > Error in summary.manova(manova_fraction2) : residuals have rank 18 < 30
> >
> > ​Is this error possibly due to high correlation between my variables?
> >
>
> Nope. Too few observations. For classical MANOVA, you need  > p degrees of
> freedom to determine the covariance matrix with full rank. As far as I can
> tell, you have only 21 observations (21-3=18 degrees of freedom) for your
> p=30 response variables.
>
> > Many thanks in advance,
>
> --
> Peter Dalgaard, Professor,
> Center for Statistics, Copenhagen Business School
> Solbjerg Plads 3, 2000 Frederiksberg, Denmark
> Phone: (+45)38153501
> Email: pd.mes at cbs.dk <javascript:;>  Priv: PDalgd at gmail.com <javascript:;>
>
>
>
>
>
>
>
>
>

-- 
Gian Maria Niccolò Benucci, PhD
University of Perugia
Dept. of Agricultural, Food and Environmental Sciences
Borgo XX Giugno, 74
06121 - Perugia, ITALY
Tel: +390755856417
Email: gian.benucci at gmail.com


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