The contingency table lists the variable values so that the first table
cell contains the frequency of positive exposure and response. PROC FREQ does
not truncate the formatted variable values that are more than 16 characters
but uses multiple lines to show Exposure levels.
PROC FREQ displays a warning message that sample size requirements may
not be met for the asymptotic chisquare tests. The exact tests are appropriate
when sample size is small.
Because the alternative hypothesis for this analysis states that coronary
heart disease was more likely to be associated with a highfat diet, a onesided
test is needed. Fisher's exact test (rightsided) tests that the probability
of heart disease in the highfat group exceeds the probability of heart disease
in the lowfat group.
The odds ratio, which provides an estimate of the relative risk when
an event is rare, indicates that the odds of heart disease are 8.25 times
higher in the high fat diet group. However, the wide confidence limits indicate
that this estimate has low precision.
