title: Inter-rater agreement in Python (Cohen's Kappa)
body: <p>I have ratings for 60 cases by 3 raters. These are in lists organized by document - the first element refers to the rating of the first document, the second of the second document, and so on:</p>
  
  <pre><code>rater1 = [-8,-7,8,6,2,-5,...]
  rater2 = [-3,-5,3,3,2,-2,...]
  rater3 = [-4,-2,1,0,0,-2,...]
  </code></pre>
  
  <p>Is there a python implementation of Cohen's Kappa somewhere? I couldn't find anything in numpy or scipy, and nothing here on stackoverflow, but maybe I missed it? This is quite a common statistic, so I'm surprised I can't find it for a language like Python.</p>