Hi all,

I am fairly new to R and I am trying to run mvpart and create a MRT using
explanatory variables and covariables. I've been following the procedures in
Numerical Ecoogy with R.

The command (no covariables) which works fine -

ABUNDTMRT <- mvpart(abundance ~
.,factors,margin=0.08,cp=0,xv="1se",xval=nrow(abundance),xvmult=100,which=4)

where abundance is 4th root transformed fish abundance (103 species x 168
samples), and factors is the relief (high, medium, low profile, sand
inundated reef, flat), benthos (coral, sessile inverts, kelp, macroalgae,
seagrass, sand), depth (continuous in meters), latitude, and longitude of
each sample.

To try and incorporate spatial autocorrelation (as a covariate) into this I
have been trying the command -

ABUNDTMRT <- mvpart(abundance ~ environ + spatial,
data.frame,margin=0.08,cp=0,xv="1se",xval=nrow(abundance),xvmult=100,which=4)

where abundance is as above, environ is the environmental factors (from
above) and spatial is the eigenfunctions from a PCNM analysis. data.frame is
the environ and spatial factors as a data.frame.

This gives the error -

"Error in `[[<-.data.frame`(`*tmp*`, preds, value = c(72L, 72L, 80L, 72L,
 :
  replacement has 504 rows, data has 168"

As I am new to this, I am not sure if I am entering an incorrect formula
when trying to include the covariables, or if this is just something which
mvpart cannot do.

Thanks.

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