verify, test_verify: fixed odds ratio (and subsequent Yule's Q calc)

drsteve · May 29, 2018 · efd0420 · efd0420
1 parent 717c24a
commit efd0420
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Showing 2 changed files with 13 additions and 1 deletion.
diff --git a/test_verify.py b/test_verify.py
@@ -78,6 +78,16 @@ def test_MatthewsCC_known2(self):
         ctab = verify.Contingency2x2([[0, 24], [327, 0]])
         self.assertEqual(ctab.MatthewsCC(), -1)
 
+    def test_oddsRatio_known(self):
+        '''Test Odds ratio calculation with example given by Thornes and Stephenson'''
+        ctab = verify.Contingency2x2([[29, 6], [4, 38]])
+        self.assertAlmostEqual(ctab.oddsRatio(), 45.9, places=1)
+
+    def test_YuleQ_known(self):
+        '''Test Yule's Q (ORSS) calculation with example given by Thornes and Stephenson'''
+        ctab = verify.Contingency2x2([[29, 6], [4, 38]])
+        self.assertAlmostEqual(ctab.yuleQ(), 0.96, places=2)
+
     def test_Finley_n(self):
         ctab = verify.Contingency2x2(self.Finley)
         self.assertEqual(ctab.sum(), 2803)

diff --git a/verify.py b/verify.py
@@ -1175,7 +1175,9 @@ def oddsRatio(self):
              This is also added to the attrs attribute of the table object
         '''
         a,b,c,d = self._abcd()
-        odds = a*d/b*c
+        numer = a*d
+        denom = b*c
+        odds = numer/denom
 
         self.attrs['OddsRatio'] = odds
         return self.attrs['OddsRatio']