Conceptual and Visual Models for Categorical Data

Abstract

A dynamic conceptual model for categorical data is described that likens observations to gas molecules in a pressure chamber. In this physical model frequency corresponds to pressure, and fitting a statistical model by maximum likelihood corresponds to minimizing energy or balancing of forces. The model provides neat explanations of many results for categorical data, extends readily to multiway tables, and provides a rationale for the graphic representation of counts by area or visual density.

Key Words:

• Graphical display
• Iterative proportional fitting
• Maximum likelihood
• Mechanical models
• Mosaic display
• Newton-Raphson iteration