On 16.05.2011 22:07, Songer, Katherine B - DNR wrote:
Hi R experts,
I'm attempting to run Linear Discriminant Analysis using the lda function in
the MASS package. I've got around 50 predictor variables and one response
variable. My response variable has 5 numeric categories that represent
different clusters of fish abundance data (clusters were developed using
Bray-Curtis and NMDS), and my predictor variables are environmental variables
that might influence the fish data. These data all came from 68 sampling
locations.
I'm getting an error message:
DALogFish<-lda(Cluster~DrainArea+Flow+StrmWidth+Gradient+NatComm+FishIBIUsed
+QHEI+QHEIsub+QHEImwh_h+QHEIcov+QHEIchan+QHEIrip+QHEIpool+QHEIrif+QHEIgrads+
QHEIgradv+QHEImwh+QHEIcovtype+QHEIwwh+QHab+QHabBuff+QHabEros+QhabPool+
QHabWDRatio+QHabRif+QHabFines+QHabCov+QHabRating+QHabSize+TP+TKN+NH3+NH3Min
+NO3NO2N+BOD+TSS+TSSMax+TDS+SSC+SSCMax+Chloride+Sulfate+Ecoli+ChlA+DOper+
DOperMin+DOperMin1_5+DOmgL+DOmgLMean+DOmgLMax+Cond+pH+pHMax+Trans+Temp+
TempMin+Temp4+Crop100+Crop500+CropSub+Dev100+Dev500+DevSub+For100+For500+
ForSub+Pas100+Pas500+PasSub+Wat100+Wat500+WatSub+Wet100+Wet500+WetSub+
Undev100+Undev500+UndevTotal+Undev100NoPas+Undev500NoPas+UndevTotNoPas,
data=AllData1, na.action="na.omit", CV=TRUE)
Error in lda.default(x, grouping, ...) :
variables 10 38 42 appear to be constant within groups
When I look at the variables listed, they don't appear "constant within the
groups" to me.
We do not know, since we do not have the data.
I'm new to LDA and am wondering what this error means... Are my data somehow
not in the right format? Should I remove colinear variables? (All variables
have been normalized.)
Yes, colinear variables should be removed. Note als, that you have
roughly as many (or even more) variables in the model than observations.
This won't work either. I think you should read some textbook on the
mechanisms behind an LDA.
Uwe Ligges
Thanks very much!
Katie
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