Linear equality constraints in the general linear mixed model

Academic Article


  • Scientists may wish to analyze correlated outcome data with constraints among the responses, For example, piecewise linear regression in a longitudinal data analysis can require use of a general linear mixed model combined with linear parameter constraints. Although well developed for standard univariate models, there are no general results that allow a data analyst to specify a mixed model equation in conjunction with a set of constraints on the parameters. We resolve the difficulty by precisely describing conditions that allow specifying linear parameter constraints that insure the validity of estimates and tests in a general linear mixed model. The recommended approach requires only straightforward and noniterative calculations to implement. We illustrate the convenience and advantages of the methods with a comparison of cognitive developmental patterns in a study of individuals from infancy to early adulthood for children from low-income families.
  • Authors

    Published In

  • Biometrics  Journal
  • Digital Object Identifier (doi)

    Author List

  • Edwards LJ; Stewart PW; Muller KE; Helms RW
  • Start Page

  • 1185
  • End Page

  • 1190
  • Volume

  • 57
  • Issue

  • 4