| Dealing with baseline differences: two principles and two dilemmas. | |
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MedLine Citation:
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PMID: 9987061 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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Two principles are presented that describe directional confounds associated with baseline differences: Principle 1: Change scores are confounded with baseline whenever data are skewed. Principle 2: When baseline differences are real, ANCOVA has a directional bias that magnifies differences in one direction and masks those in the other direction. Both principles involve a directional bias that is related to the direction of baseline difference and the direction of the hypothesized difference in change. Ethical dilemmas arise if decisions (whether or not to transform, whether or not to use ANCOVA) are chosen in order to maximize power by capitalizing on the directional bias and Type 1 error. |
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Authors:
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J Jamieson |
Publication Detail:
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Type: Journal Article |
Journal Detail:
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Title: International journal of psychophysiology : official journal of the International Organization of Psychophysiology Volume: 31 ISSN: 0167-8760 ISO Abbreviation: Int J Psychophysiol Publication Date: 1999 Jan |
Date Detail:
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Created Date: 1999-05-05 Completed Date: 1999-05-05 Revised Date: 2000-12-18 |
Medline Journal Info:
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Nlm Unique ID: 8406214 Medline TA: Int J Psychophysiol Country: NETHERLANDS |
Other Details:
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Languages: eng Pagination: 155-61 Citation Subset: IM |
Affiliation:
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Department of Psychology, Lakehead University, Thunder Bay, ON, Canada. john.jamieson@lakeheadu.ca |
Export Citation:
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| MeSH Terms | |
Descriptor/Qualifier:
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Analysis of Variance* Confounding Factors (Epidemiology)* Data Interpretation, Statistical* Decision Making Ethics, Professional Longitudinal Studies* Psychophysiology / methods*, standards Research Design / standards |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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