SOC210 Lecture 15: Bivariate measures of association for ordinal level variables
12 May 2017
School
Department
Course
Professor
Document Summary
Soc 210 lecture 15 bivariate measures of association for ordinal level variables. Measures of association for two collapse ordinal variables. Measures both strength and direction of a relationship. Based on the logic of pairs of cases. To compute gamma, first find ns and nd. Ns = total number of similar pairs. Nd = total number of dissimilar pairs. Example: first pair = person 1 and person 2 same order on both variables similar (ns, second pair = person 3 and person 4. G = (ns - nd) / (ns + nd) Strength of the relationship ranges from 0 (no association) to +-1 (perfect association) if ns > nd, then gamma will be positive if ns < nd, then gamma will be negative. When variables are not coded from low to high, exercise caution in using the sign (+ or -) of gamma to determine actual direction of the relationship. Gamma tends to exaggerate the real strength of association.
