Document Detail


Robust step-down tests for multivariate independent group designs.
MedLine Citation:
PMID:  17971269     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
A composite step-down procedure, in which a set of step-down tests are summarized collectively with Fisher's combination statistic, was considered to test for multivariate mean equality in two-group designs. An approximate degrees of freedom (ADF) composite procedure based on trimmed/Winsorized estimators and a non-pooled estimate of error variance is proposed, and compared to a composite procedure based on trimmed/Winsorized estimators and a pooled estimate of error variance. The step-down procedures were also compared to Hotelling's T (2) and Johansen's ADF global procedure based on trimmed estimators in a simulation study. Type I error rates of the pooled step-down procedure were sensitive to covariance heterogeneity in unbalanced designs; error rates were similar to those of Hotelling's T (2) across all of the investigated conditions. Type I error rates of the ADF composite step-down procedure were insensitive to covariance heterogeneity and less sensitive to the number of dependent variables when sample size was small than error rates of Johansen's test. The ADF composite step-down procedure is recommended for testing hypotheses of mean equality in two-group designs except when the data are sampled from populations with different degrees of multivariate skewness.
Authors:
Lisa M Lix; Rachel T Fouladi
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  The British journal of mathematical and statistical psychology     Volume:  60     ISSN:  0007-1102     ISO Abbreviation:  Br J Math Stat Psychol     Publication Date:  2007 Nov 
Date Detail:
Created Date:  2007-10-31     Completed Date:  2008-01-18     Revised Date:  2009-11-11    
Medline Journal Info:
Nlm Unique ID:  0004047     Medline TA:  Br J Math Stat Psychol     Country:  England    
Other Details:
Languages:  eng     Pagination:  245-65     Citation Subset:  IM    
Affiliation:
Department of Community Health Sciences, University of Manitoba, Winnipeg, MB, Canada R3E 3P5. lisa_lix@cpe.umanitoba.ca
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MeSH Terms
Descriptor/Qualifier:
Humans
Models, Psychological*
Psychology / methods*,  statistics & numerical data*

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine


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