Compare methods

	UNIDIFF Mobility Model	Goodman Association Model
Field	Sociology	Sociology
Family	Regression model	Regression model
Year of origin	1992	1979
Originator	Yu Xie; Robert Erikson & John Goldthorpe (parallel)	Leo A. Goodman
Type	Log-multiplicative model for comparing association across tables	Log-multiplicative model for association in ordered contingency tables
Seminal source	Xie, Y. (1992). The log-multiplicative layer effect model for comparing mobility tables. American Sociological Review, 57(3), 380–395.	Goodman, L. A. (1979). Simple models for the analysis of association in cross-classifications having ordered categories. Journal of the American Statistical Association, 74(367), 537–552.
Aliases	UNIDIFF model, log-multiplicative layer effect model, uniform difference model, Xie-Erikson-Goldthorpe model	RC association model, row-column association model, log-multiplicative model, RC(M) model
Related	4	5
Summary	The uniform difference (UNIDIFF) model, equivalently the log-multiplicative layer effect model, compares the strength of origin–destination association across several mobility tables — countries, time periods, or birth cohorts. It assumes the tables share a common pattern of association ψ_ij but allows the overall strength of that pattern to differ by a single layer-specific multiplier φ_k. A φ_k above one means stronger origin effects (less fluidity) in that layer; below one means greater fluidity.	Goodman's association models, especially the row-column (RC) model, analyze the association in a two-way contingency table by representing it as a product of estimated scores for the row categories and scores for the column categories, scaled by an intrinsic association parameter. Introduced by Leo Goodman in 1979, they are log-multiplicative rather than purely log-linear, allowing ordered categories to be assigned data-driven scores and the strength of association to be summarized in a single, interpretable coefficient.