ABSTRACT
A contingency table is used to show cross-classified categorical data on two or more
variables. The variables can be nominal or ordinal. A nominal variable has cate-
gories with no natural ordering; for example, consider the automotive companies
Ford, General Motors and Toyota. An ordering could be imposed using some crite-
rion like sales, but there is nothing inherent in the categories that makes any particular
ordering obvious. An ordinal variable does have a natural default ordering. For ex-
ample, a disease might be recorded as absent, mild or severe. The five-point Likert
scale ranging through strongly disagree, disagree, neutral, agree and strongly agree
is another example.
