n a randomized controlled study of flu vaccine, patients were randomly allocated to two groups, one group was given the new vaccine and the other a saline placebo. The responses were titre levels of hemagglutinin inhibiting antibody in blood 6 weeks after the vaccination. The responses were categorized as "small","moderate" and "large". The number of patients in each treatment group is predetermined. The data is displayed in Table 1. We want to know if the pattern of response is independent of the treatment group