title: PC program for assessing the relationship between rate of change and initial value.
abstract: A menu-driven PC program implementing Blomqvist's [J. Am. Stat. Assn. 72, 746-749, 1977] method for assessing the relationship between rate of change and initial value is described, illustrated and made available. It is shown that the naive approach to this problem--computing the correlation between the initial value and either the amount or rate of change--results in a negatively biased estimator. The extent of this bias can be dramatic and may lead investigators to conclude that a negative correlation is present when none exists; or that there is no correlation when in fact the correlation is positive. Blomqvist's (maximum likelihood) estimator avoids this bias, and is obtained by a transformation of the naive estimator.
authors.affiliation: Department of Biologic and Materials Sciences, Dental School, University of Michigan, Ann Arbor 48109, USA.
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; D015982:Bias; D002648:Child; D005544:Forecasting; D006801:Humans; D007700:Kinetics; D016013:Likelihood Functions; D008297:Male; D008334:Mandible / Q000254:growth & development; D008838:Microcomputers; D015233:Models, Statistical; D015203:Reproducibility of Results; D012984:Software