factor / intiger
Dear List I have a excel spread sheet with 5 columns that contain categorical data. I have recoded them to numbers A B C 0 0 0 1 1 1 2 2 2 3 3 4 5 etc When i read it into R and do str(dataframe) i get - $ A : int 1 1 1 1 1 1 1 1 1 1 ... $ B : int 1 1 1 1 1 1 1 1 1 1 ... $ C : int 0 0 0 0 0 0 0 0 0 0 ... $ D : int 0 0 0 0 0 0 0 0 0 0 ... $ E : int 0 0 0 0 0 0 0 0 0 0 ... I then realised they should probably be factors instead of integers so used as.factor to convert them - A <- as.factor(A) Now when i run the GLMM the AIC values are different from when they were integers, i have 2 questions 1. Should i not have converted the categories to numbers in the excel spreadsheet before import. 2. Why are the AIC values different when i use as.factor as opposed to keeping them as integers, and which approach is recommended? Thanks Sam