Multilevel modeling for repeated measures: Difference between revisions

Revision as of 09:23, 2 December 2014

Revision as of 12:17, 14 July 2015

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In multilevel modeling, an overall change function (e.g. linear, quadratic, cubic etc.) is fitted to the whole sample and, just as in multilevel modeling for clustered data, the [[slope]] and [[Y-intercept|intercept]] may be allowed to vary. For example, in a study looking at income growth with age, individuals might be assumed to show linear improvement over time. However, the exact intercept and slope could be allowed to vary across individuals (i.e. defined as random coefficients).

Multilevel modeling with repeated measures employs the same statistical techniques as MLM with clustered data. In multilevel modeling for repeated measures data, the measurement occasions are nested within cases (e.g. individual or subject). Thus, [[Multilevel model#Level 1 regression equation|level-1]] units consist of the repeated measures for each subject, and the [[Multilevel model#Level 1 regression equation|level-2]] unit is the individual or subject. In addition to estimating overall parameter estimates, MLM allows regression equations at the level of the individual. Thus, as a growth curve modeling technique, it allows the estimation of inter-individual differences in intra-individual change over time by modeling the variances and covariances.<ref>{{cite journal|last=Curran|first=Patrick J. |coauthorsauthor2=Obeidat, Khawla, |author3=Losardo, Diane|title=Twelve Frequently Asked Questions About Growth Curve Modeling|journal=Journal of Cognition and Development|volume=11|issue=2|pages=121–136|doi=10.1080/15248371003699969}}</ref> In other words, it allows the testing of individual differences in patterns of responses over time (i.e. growth curves). This characteristic of multilevel modeling makes it preferable to other repeated measures statistical techniques such as repeated measures-analysis of variance ([[RM-ANOVA]]) for certain research questions.

==Assumptions==

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===Multilevel Modeling versus RM-ANOVA===

Repeated measures analysis of variance ([[RM-ANOVA]]) has been traditionally used for analysis of [[repeated measures]] designs. However, violation of the assumptions of RM-ANOVA can be problematic. Multilevel modeling (MLM) is commonly used for repeated measures designs because it presents an alternative approach to analyzing this type of data with three main advantages over RM-ANOVA:<ref name=quene>{{cite journal|last=Quené|first=Hugo|coauthorsauthor2=van den Bergh, Huub|title=On multi-level modeling of data from repeated measures designs: a tutorial|journal=Speech Communication|year=2004|volume=43|issue=1-2|pages=103–121|doi=10.1016/j.specom.2004.02.004}}</ref>

::'''1. MLM has Less Stringent Assumptions:''' MLM can be used if the assumptions of constant variances (homogeneity of variance, or [[homoscedasticity]]), constant covariances (compound symmetry), or constant variances of differences scores ([[sphericity]]) are violated for RM-ANOVA. MLM allows modeling of the variance-covariance matrix from the data; thus, unlike in RM-ANOVA, these assumptions are not necessary.<ref name=cohen>{{cite book|first=Jacob Cohen|title=Applied multiple regression/correlation analysis for the behavioral sciences|publisher=Erlbaum|___location=Mahwah, NJ [u.a.]|isbn=9780805822236|edition=3. ed.}}</ref>

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*{{cite book|first1=Jacob|last1=Cohen|first2=Patricia|last2=Cohen|first3=Stephen G.|last3= West|first4=Leona S.|last4= Aiken |year=2002|title=Applied Multiple Regression/Correlation Analysis for the Behavioral Sciences|publisher=Routledge Academic|isbn=9780805822236|edition=3. ed.}}

*{{cite journal|last=Curran|first=Patrick J. |coauthorsauthor2=Obeidat, Khawla, |author3=Losardo, Diane|title=Twelve Frequently Asked Questions About Growth Curve Modeling|journal=Journal of Cognition and Development|year=2010|volume=11|issue=2|pages=121–136|doi=10.1080/15248371003699969}}

*{{cite book|last1=Fidell|first1=Barbara G.|last2= Tabachnick|first2= Linda S.|title=Using Multivariate Statistics|year=2007|publisher=Pearson/A & B|___location=Boston ; Montreal|isbn=0205459382|edition=5th ed.}}

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*{{cite journal|last=Overall|first=John|coauthors=Ahn, Chul, Shivakumar, C., Kalburgi, Yallapa|title=PROBLEMATIC FORMULATIONS OF SAS PROC.MIXED MODELS FOR REPEATED MEASUREMENTS|journal=Journal of Biopharmaceutical Statistics|year=2007|volume=9|issue=1|pages=189–216|doi=10.1081/BIP-100101008}}

*{{cite journal|last=Quené|first=Hugo|coauthorsauthor2=van den Bergh, Huub|title=On multi-level modeling of data from repeated measures designs: a tutorial|journal=Speech Communication|year=2004|volume=43|issue=1-2|pages=103–121|doi=10.1016/j.specom.2004.02.004}}

[[Category:Statistical models]]