An example in Schlotzhauer and Littell (1997) presented data from an experiment conducted by an epidemiologist who classified the disease severity of dairy cows (none, low, high) by analyzing blood samples for the presence of a bacterial disease. The size of the herd that each cow belonged to was classified as large, medium, or small. One of the aims of this study was to determine if disease severity was affected by herd size.

Herd size Severity Large Medium Small None 11 88 136 Low 18 4 19 High 9 5 9 Use a SAS program to analyze these data using proc freq. Is there any association between two variables? Use the various measures to interpret any association present considering that the two variables are ordinal and that the experimenter is planning to use herd size for predicting disease severity. Obtain confidence intervals for the measures that you discuss.