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Blinded versus unblinded estimation of a correlation coefficient to inform interim design adaptations
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Kunz, Cornelia, Stallard, Nigel, Parsons, Nicholas R., Todd, Susan and Friede, Tim (2017) Blinded versus unblinded estimation of a correlation coefficient to inform interim design adaptations. Biometrical Journal, 59 (2). pp. 344-357. doi:10.1002/bimj.201500233
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Official URL: http://doi.org/10.1002/bimj.201500233
Abstract
Regulatory authorities require that the sample size of a confirmatory trial is calculated prior to the start of the trial. However, the sample size quite often depends on parameters which might not be known in advance of the study. Misspecification of these parameters can lead to under- or overestimation of the sample size. Both situations are unfavourable as the first one decreases the power and the latter one leads to a waste of resources. Hence, designs have been suggested that allow a re-assessment of the sample size in an ongoing trial. These methods usually focus on estimating the variance. However, for some methods the performance depends not only on the variance but also on the correlation between measurements. We develop and compare different methods for blinded estimation of the correlation coefficient which are less likely to introduce operational bias when the blinding is maintained. Their performance with respect to bias and standard error is compared to the unblinded estimator. We simulated two different settings: one assuming that all group means are the same and one assuming that different groups have different means. Simulation results show that the naïve (onesample) estimator is only slightly biased and has a standard error comparable to that of the unblinded estimator. However, if the group means differ, other estimators have better performance depending on the sample size per group and the number of groups.
| Item Type: | Journal Article | |||||||||
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| Subjects: | R Medicine > R Medicine (General) | |||||||||
| Divisions: | Faculty of Medicine > Warwick Medical School > Health Sciences Faculty of Medicine > Warwick Medical School > Health Sciences > Statistics and Epidemiology Faculty of Medicine > Warwick Medical School |
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| Library of Congress Subject Headings (LCSH): | Clinical trials -- Statistical methods -- Research | |||||||||
| Journal or Publication Title: | Biometrical Journal | |||||||||
| Publisher: | Wiley - V C H Verlag GmbH & Co. KGaA | |||||||||
| ISSN: | 0323-3847 | |||||||||
| Official Date: | March 2017 | |||||||||
| Dates: |
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| Volume: | 59 | |||||||||
| Number: | 2 | |||||||||
| Page Range: | pp. 344-357 | |||||||||
| DOI: | 10.1002/bimj.201500233 | |||||||||
| Status: | Peer Reviewed | |||||||||
| Publication Status: | Published | |||||||||
| Access rights to Published version: | Open Access | |||||||||
| Funder: | Medical Research Council (Great Britain) (MRC), Seventh Framework Programme (European Commission) (FP7) | |||||||||
| Grant number: | Grant number G1001344 (MRC), FP HEALTH 2013 -- 602144 (FP7) | |||||||||
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