An Exploration of Variability Due to Low Power in Structural MRI Studies of Bilingualism

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dc.contributor.advisorHernandez, Arturo E.
dc.contributor.committeeMemberFrancis, David J.
dc.contributor.committeeMemberTamber-Rosenau, Benjamin J.
dc.contributor.committeeMemberChiarello, Christine
dc.creatorMunson, Brandin A.
dc.creator.orcid0000-0003-0025-4759
dc.date.accessioned2019-06-24T19:30:49Z
dc.date.available2019-06-24T19:30:49Z
dc.date.createdDecember 2018
dc.date.issued2018-12
dc.date.submittedDecember 2018
dc.date.updated2019-06-24T19:30:49Z
dc.description.abstractThe adequacy of replicability among psychological findings has previously been questioned, especially for neuroscientific fields of research. Researchers increasingly point towards the negative effects of low power on replicability of findings. Though decreased sensitivity in smaller samples is a well-known consequence of inadequate power, many overlook the increased likelihood of inflated observed effects and weakened positive predictive values. The aim of this study is to reveal the expected degrees of uncertainty among neuroimaging findings by conducting tests in different sample sizes from a larger-than-average sample, in an area of research with wide-ranging findings that have been proposed by some to be due in part to inadequate sample sizes: bilingual-monolingual structural brain differences. Bilinguals (n = 216) were compared with monolinguals (n = 146) using grey matter density in whole-brain analyses and grey matter volume measures across region-of-interest tests. Variability among findings were compared with the true full-sample findings, and taken in the context of expected differences within the larger bilingualism neuroimaging literature. Results demonstrate excessive variability across the lowest sample sizes (e.g. samples totaling 20 – 80 participants), and this is explored through the trends of subsample outcomes and effect sizes across sample sizes. The extent to which infrequently utilized methods such as multivariate analyses of covariance (MANCOVAs) and Bayes Factors can improve the accuracy of results at lower sample sizes were also explored. It is our hope that this study helps to demonstrate the influences of power on expected variability among sample findings, especially for bilingual researchers and any researchers interested in exploring group differences using neuroimaging.
dc.description.departmentPsychology, Department of
dc.format.digitalOriginborn digital
dc.format.mimetypeapplication/pdf
dc.identifier.urihttps://hdl.handle.net/10657/4080
dc.language.isoeng
dc.rightsThe author of this work is the copyright owner. UH Libraries and the Texas Digital Library have their permission to store and provide access to this work. Further transmission, reproduction, or presentation of this work is prohibited except with permission of the author(s).
dc.subjectReplicability
dc.subjectSample size
dc.subjectPower
dc.subjectNeuroimaging
dc.subjectMRI
dc.subjectBilingualism
dc.titleAn Exploration of Variability Due to Low Power in Structural MRI Studies of Bilingualism
dc.type.dcmiText
dc.type.genreThesis
thesis.degree.collegeCollege of Liberal Arts and Social Sciences
thesis.degree.departmentPsychology, Department of
thesis.degree.disciplineDevelopmental, Behavioral, and Cognitive Neuroscience
thesis.degree.grantorUniversity of Houston
thesis.degree.levelDoctoral
thesis.degree.nameDoctor of Philosophy

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