I have a dataset which contains 100 observations, and I asked three expert to describe each observation by one of the letters {A,B,C}. The following three tables shows a sample of the dataset with the description from the three experts. enter image description here I want to use Cronbach's alpha measure of internal consistency? Can anyone help me to calculate the alpha value?

  • $\begingroup$ Do the letters A, B, and C have an ordered relationship or are they nominal categories? $\endgroup$ – Jeffrey Girard Apr 28 '16 at 15:58
  • $\begingroup$ they don't have an ordered relationship, it's just nominal categories. $\endgroup$ – Omar14 Apr 28 '16 at 17:31
  • $\begingroup$ Cronbach's alpha is not appropriate for nominal categories. Do you just want to see how much the three experts agreed? $\endgroup$ – Jeffrey Girard Apr 28 '16 at 17:32
  • $\begingroup$ Yes, I'm looking to see how the three experts agreed? like saying: the three experts agreed on 90% of the dataset. But why Cronbach's alpha does not work on nominal categories (or categorical data)? $\endgroup$ – Omar14 Apr 28 '16 at 17:35
  • $\begingroup$ Cronbach's alpha estimates reliability by partitioning the variance and covariance of the data. However, these values are not meaningful with nominal categories. You should use an index of categorical agreement instead. Options include accuracy, Cohen's kappa, Scott's pi, Bennett's S, etc. $\endgroup$ – Jeffrey Girard Apr 28 '16 at 18:13

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