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Efficient design of cluster randomized trials with treatment-dependent costs and treatment-dependent unknown variances
- Source :
- Statistics in Medicine, 37(21), 3027-3046. John Wiley & Sons Inc., Statistics in Medicine
- Publication Year :
- 2018
- Publisher :
- Wiley, 2018.
-
Abstract
- Cluster randomized trials evaluate the effect of a treatment on persons nested within clusters, where treatment is randomly assigned to clusters. Current equations for the optimal sample size at the cluster and person level assume that the outcome variances and/or the study costs are known and homogeneous between treatment arms. This paper presents efficient yet robust designs for cluster randomized trials with treatment-dependent costs and treatment-dependent unknown variances, and compares these with 2 practical designs. First, the maximin design (MMD) is derived, which maximizes the minimum efficiency (minimizes the maximum sampling variance) of the treatment effect estimator over a range of treatment-to-control variance ratios. The MMD is then compared with the optimal design for homogeneous variances and costs (balanced design), and with that for homogeneous variances and treatment-dependent costs (cost-considered design). The results show that the balanced design is the MMD if the treatment-to control cost ratio is the same at both design levels (cluster, person) and within the range for the treatment-to-control variance ratio. It still is highly efficient and better than the cost-considered design if the cost ratio is within the range for the squared variance ratio. Outside that range, the cost-considered design is better and highly efficient, but it is not the MMD. An example shows sample size calculation for the MMD, and the computer code (SPSS and R) is provided as supplementary material. The MMD is recommended for trial planning if the study costs are treatment-dependent and homogeneity of variances cannot be assumed.
- Subjects :
- Statistics and Probability
Optimal design
Epidemiology
study costs
01 natural sciences
law.invention
010104 statistics & probability
03 medical and health sciences
0302 clinical medicine
Randomized controlled trial
law
Statistics
Journal Article
Cluster (physics)
maximin design
Cluster Analysis
Humans
030212 general & internal medicine
Cluster randomised controlled trial
optimal design
0101 mathematics
Research Articles
health care economics and organizations
Randomized Controlled Trials as Topic
Mathematics
Models, Statistical
Homogeneity (statistics)
heterogeneous variance
Estimator
Minimax
sample size
Research Design
Sample size determination
cluster randomized trial
Research Article
Subjects
Details
- ISSN :
- 02776715
- Volume :
- 37
- Database :
- OpenAIRE
- Journal :
- Statistics in Medicine
- Accession number :
- edsair.doi.dedup.....8c59e77259cab06782cfd16bacfb625c