Title: The Misspecification of the Covariance Structures in Multilevel Models for Single-Case Data: A Monte Carlo Simulation Study
Authors: Moeyaert, Mariola ×
Ugille, Maaike
Ferron, John
Beretvas, S. Natasha
Van Den Noortgate, Wim #
Issue Date: 2015
Publisher: Edwards Bros
Series Title: Journal of Experimental Education vol:84 issue:3 pages:473-509
Abstract: The impact of misspecifying covariance matrices at the second and the third levels of the three-level model on inferences regarding the overall treatment effect and (co)variances estimates is evaluated by means of a simulation study and an empirical illustration is given. The results indicate that ignoring an existing covariance has no effect on the treatment effect estimate. In addition, the between-case variance estimates are unbiased and well estimated either when covariance is modeled or ignored. If the research interest lies in the between-study variance estimate, including at least 30 studies is warranted to get unbiased and precise estimates. Modeling covariance does not result in less biased and more precise between-study variance estimates as the between-study covariance estimate is extremely biased. As a consequence, single-case researchers can use either the model ignoring or modeling covariance when the research interest lies in the overall treatment effect estimate and/or the between-case variance. In addition, when the research interest lies on the between-case covariance, the model including covariance results in unbiased between-case variance estimates. The three-level model appears to be less appropriate to estimate the between-study variance if less than 30 studies are included.
ISSN: 0022-0973
Publication status: published
KU Leuven publication type: IT
Appears in Collections:Methodology of Educational Sciences
Faculty of Psychology and Educational Sciences, Campus Kulak Kortrijk – miscellaneous
Faculty of Psychology and Educational Sciences - miscellaneous
× corresponding author
# (joint) last author

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