Testing for negligible interaction: A coherent and robust approach.

dc.contributor.authorCribbie, Robert
dc.contributor.authorRagoonanan, Chantal
dc.contributor.authorCounsell, Alyssa
dc.date.accessioned2017-06-26T13:19:31Z
dc.date.available2017-06-26T13:19:31Z
dc.date.issued2016
dc.description.abstractResearchers often want to demonstrate a lack of interaction between two categorical predictors on an outcome. To justify a lack of interaction, researchers typically accept the null hypothesis of no interaction from a conventional analysis of variance (ANOVA). This method is inappropriate as failure to reject the null hypothesis does not provide statistical evidence to support a lack of interaction. This study proposes a bootstrap-based intersection-union test for negligible interaction that provides coherent decisions between the omnibus test and post hoc interaction contrast tests and is robust to violations of the normality and variance homogeneity assumptions. Further, a multiple comparison strategy for testing interaction contrasts following a nonsignificant omnibus test is proposed. Our simulation study compared the Type I error control, omnibus power and per-contrast power of the proposed approach to the noncentrality-based negligible interaction test of Cheng and Shao (2007). For 2 x 2 designs, the empirical Type I error rates of the Cheng and Shao test were very close to the nominal α level when the normality and variance homogeneity assumptions were satisfied, however only our proposed bootstrapping approach was satisfactory under nonnormality and/or variance heterogeneity. In general a x b designs, although the omnibus Cheng and Shao test, as expected, is the most powerful, it is not robust to assumption violation and results in incoherent omnibus and interaction contrast decisions that are not possible with the intersection-union approach.en_US
dc.description.sponsorshipSocial Sciences and Humanities Research Council of Canada
dc.identifier.citationCribbie, R. A., Ragoonanan, C., & Counsell, A. (2016). Testing for negligible interaction: A coherent and robust approach. British Journal of Mathematical and Statistical Psychology, 69(2), 159-174. doi: 10.1111/bmsp.12066.
dc.identifier.uri10.1111/bmsp.12066en_US
dc.identifier.urihttp://hdl.handle.net/10315/33241
dc.language.isoenen_US
dc.publisherWileyen_US
dc.rights.articlehttp://onlinelibrary.wiley.com/doi/10.1111/bmsp.12066/full
dc.rights.journalhttp://onlinelibrary.wiley.com/journal/10.1111/(ISSN)2044-8317en_US
dc.titleTesting for negligible interaction: A coherent and robust approach.
dc.typeArticleen_US

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