> On 30 Mar 2015, at 17:11 , Gian Maria Niccolò Benucci
> <gian.benu...@gmail.com> 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....@cbs.dk Priv: pda...@gmail.com
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