| Tests for qualitative treatment-by-centre interaction using a 'pushback' procedure. | |
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MedLine Citation:
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PMID: 8341864 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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In multicentre clinical trials using a common protocol, the centres are usually regarded as being a fixed factor, thus allowing any treatment-by-centre interaction to be omitted from the error term for the effect of treatment. However, we feel it necessary to use the treatment-by-centre interaction as the error term if there is substantial evidence that the interaction with centres is qualitative instead of quantitative. To make allowance for the estimated uncertainties of the centre means, we propose choosing a reference value (for example, the median of the ordered array of centre means) and converting the individual centre results into standardized deviations from the reference value. The deviations are then reordered, and the results 'pushed back' by amounts appropriate for the corresponding order statistics in a sample from the relevant distribution. The pushed-back standardized deviations are then restored to the original scale. The appearance of opposite signs among the destandardized values for the various centres is then taken as 'substantial evidence' of qualitative interaction. Procedures are presented using, in any combination: (i) Gaussian, or Student's t-distribution; (ii) order-statistic medians or outward 90 per cent points of the corresponding order statistic distributions; (iii) pooling or grouping and pooling the internally estimated standard deviations of the centre means. The use of the least conservative combination--Student's t, outward 90 per cent points, grouping and pooling--is recommended. |
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Authors:
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J L Ciminera; J F Heyse; H H Nguyen; J W Tukey |
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Publication Detail:
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Type: Journal Article |
Journal Detail:
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Title: Statistics in medicine Volume: 12 ISSN: 0277-6715 ISO Abbreviation: Stat Med Publication Date: 1993 Jun |
Date Detail:
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Created Date: 1993-09-02 Completed Date: 1993-09-02 Revised Date: 2007-11-15 |
Medline Journal Info:
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Nlm Unique ID: 8215016 Medline TA: Stat Med Country: ENGLAND |
Other Details:
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Languages: eng Pagination: 1033-45 Citation Subset: IM |
Affiliation:
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Merck Research Laboratories, West Point, PA 19486. |
Export Citation:
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| MeSH Terms | |
Descriptor/Qualifier:
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Clinical Trials as Topic
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methods* Humans Multicenter Studies as Topic / methods* Normal Distribution |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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