I am looking to calculate Cohen's kappa for multiple items in a scale (15 items, with two raters). The problem is that for 12 of the items the responses available to the raters were binary (yes, no). The remaining three are categorical responses with more than two choices (e.g. cat1,cat2,cat3,cat4). Does it make sense to use the Kappa statistic across both types of variables at the same time? Or should I calculate Kappa separately for the binary variables and then again for the non-binary variables?