Marginal inhomogeneity models for square contingency tables with nominal categories

Abstract

For the analysis of square contingency tables with nominal categories, this paper proposes two kinds of models that indicate the structure of marginal inhomogeneity. One model states that the absolute values of log odds of the row marginal probability to the corresponding column marginal probability for each category i are constant for every i. The other model states that, on the condition that an observation falls in one of the off-diagonal cells in the square table, the absolute values of log odds of the conditional row marginal probability to the corresponding conditional column marginal probability for each category i are constant for every i. These models are used when the marginal homogeneity model does not hold, and the values of parameters in the models are useful for seeing the degree of departure from marginal homogeneity for the data on a nominal scale. Examples are given.

Keywords:

• Asymmetry
• conditional probability
• nominal category
• marginal homogeneity
• marginal inhomogeneity
• model
• square table

Acknowledgement

The authors thank a referee for the helpful comments.