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PubMed · 8023048

Studying the relationship between change and initial value in longitudinal studies.

G O Zerbe·M C Wu·D M Zucker
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Abstract

Blomqvist's problem of studying the relationship between change and initial value in a linear growth curve setting is reformulated from a random effects model perspective. First, a maximum likelihood estimate of the between-individual covariance matrix for a simple linear regression model with stochastic parameters is obtained via an EM algorithm as discussed by Laird and Ware. Second, the regression coefficient of the individual-specific slopes on the individual-specific intercepts is estimated as a ratio of elements of the between-individual covariance matrix as discussed by Zucker et al. Then a Fieller's type confidence interval for this ratio is proposed. Discussion is facilitated by recognizing the Laird-Ware model as a special case of a more general model discussed by Hocking.

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AlgorithmsData Interpretation, StatisticalHumansLikelihood FunctionsLongitudinal StudiesModels, StatisticalRegression AnalysisJournal ArticleResearch Support, U.S. Gov't, P.H.S.

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G O Zerbe, M C Wu, D M Zucker. Studying the relationship between change and initial value in longitudinal studies.. https://doi.org/10.1002/sim.4780130536

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