I have been reading up on MANOVA and come across the common complication 
requiring a large number of degrees of freedom. After performing Procrustes 
superimpositions on my landmark configurations, along with my small sample 
sizes, is not allowing me to perform MANOVA tests.

I have read that one can fix this problem by replacing the coordinates with 
principal components. The coding from my information source is very vague, 
but I've been trying some different things. Below is my code - note the 
error message at the bottom. 

AISarray <- two.d.array(AIS.shape)

ID <- c(1, 2, 2, 2, 2, 2, 2, 2, 3, 3, 3)
Depth <- c(3, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5)
Region <- c(7, 8, 8, 8, 8, 8, 8, 8, 5, 5, 5)
RR <- c(2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2)
CDR <- c(2, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1)

AISdf <- cbind(AISarray, ID, Depth, Region, RR, CDR)

specs <- as.factor(AISdf[,51])
depth <- as.factor(AISdf[,52])
region <- as.factor(AISdf[,53])
rr <- as.factor(AISdf[,54])
cdr <- as.factor(AISdf[,55])

AIS.PC <- prcomp(AISarray)
summary(manova(lm(AIS.PC~specs*region)))     #NOT WORKING
Error in model.frame.default(formula = AIS.PC ~ specs * region, 
drop.unused.levels = TRUE) : 
  invalid type (list) for variable 'AIS.PC'

It seems MANOVA requires a data frame, but replacing the coordinates with 
principal components turns it into a list. I cannot find any other 
information on this matter. Any help would be much appreciated. 
Thanks, 

Brenna Hays
Research Assistant, Master's Student
Nova Southeastern University

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