ANOVA: Degrees of freedom almost all equal 1

Question

I have a data set that begins like this:

> d.weight
    R   N   P  C D.weight
1   1   0   0 GO     45.3
2   2   0   0 GO     34.0
3   3   0   0 GO     19.         


        

Answer 1

R determines whether it should treat variables as categorical (ANOVA-type analysis) or continuous (regression-type analysis) by checking whether they are numeric or factor variables. Most simply, you can convert your predictor (independent) variables to factors via

facs <- c("R","N","P")
d.weight[facs] <- lapply(d.weight[facs],factor) 

If you want to create auxiliary variables instead of overwriting you could do something like

for (varname in facs) {
   d.weight[[paste0("f",varname)]] <- factor(d.weight[[varname]])
}

There might be a more compact way to do it but that should serve ...