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- Title
Inference for the treatment effect in multiple-period cluster randomised trials when random effect correlation structure is misspecified.
- Authors
Kasza, Jessica; Forbes, Andrew B
- Abstract
Multiple-period cluster randomised trials, such as stepped wedge or cluster cross-over trials, are being conducted with increasing frequency. In the design and analysis of these trials, it is necessary to specify the form of the within-cluster correlation structure, and a common assumption is that the correlation between the outcomes of any pair of subjects within a cluster is identical. More complex models that allow for correlations within a cluster to decay over time have recently been suggested. However, most software packages cannot fit these models. As a result, practitioners may choose a simpler model. We analytically examine the impact of incorrectly omitting a decay in correlation on the variance of the treatment effect estimator and show that misspecification of the within-cluster correlation structure can lead to incorrect conclusions regarding estimated treatment effects for stepped wedge and cluster crossover trials.
- Subjects
CROSSOVER trials; INTEGRATED software; EXPERIMENTAL design; STATISTICS; RESEARCH; CLINICAL trials; ANALYSIS of variance; RESEARCH methodology; EVALUATION research; MEDICAL cooperation; COMPARATIVE studies; STATISTICAL models; CLUSTER analysis (Statistics)
- Publication
Statistical Methods in Medical Research, 2019, Vol 28, Issue 10/11, p3112
- ISSN
0962-2802
- Publication type
journal article
- DOI
10.1177/0962280218797151