title: GTRACK: a PC program for computing Goldstein's growth constancy index and an alternative measure of tracking.
abstract: This paper reviews Goldstein's 'growth constancy index,' Xi, a measure of tracking which can be used to determine whether or not individuals maintain their relative positions in the distribution of a given measurement as that distribution changes over time. We suggest that Xi is an appropriate measure of tracking when the (standardized) measurements arise in the context of a Model I ANOVA, but that the intraclass correlation coefficient, rI, may be preferred when a Model II ANOVA is applicable. We also describe--and make available--a PC program which allows the user to choose between Model I and Model II, and computes the appropriate tracking index and confidence intervals for the corresponding parameter.
authors.affiliation: Department of Biostatistics, University of Michigan, Ann Arbor 48109.
authors.forename: A M
authors.initials: AM
authors.lastname: Furey
authors.forename: C J
authors.initials: CJ
authors.lastname: Kowalski
authors.forename: E D
authors.initials: ED
authors.lastname: Schneiderman
authors.forename: S M
authors.initials: SM
authors.lastname: Willis
mesh_terms: D000465:Algorithms; D000704:Analysis of Variance; D000818:Animals; D003198:Computer Simulation; D016001:Confidence Intervals; D006128:Growth / Q000502:physiology*; D006801:Humans; D008137:Longitudinal Studies; D008253:Macaca mulatta; D008297:Male; D008334:Mandible / Q000254:growth & development; D008838:Microcomputers; D008954:Models, Biological; D015233:Models, Statistical; D012984:Software