Example: Contingency tables
Observed
Toxicity
No Toxicity Total
Treatment A 30
70
100
Treatment B 40
60
100
Total
70
130
-
Expected
Toxicity
No Toxicity Total
Treatment A 35
65
100
Treatment B 35
65
100
Total
70
130
-
=2.2
P=0.14
http://statpages.org/ctab2x2.html http://www.medcalc.org/manual/chi-square-table.php