title: Establishing normative data for multi-trial memory tests: the multivariate regression-based approach.
abstract: OBJECTIVE
  Multi-trial memory tests are widely used in research and clinical practice because they allow for assessing different aspects of memory and learning in a single comprehensive test procedure. However, the use of multi-trial memory tests also raises some key data analysis issues. Indeed, the different trial scores are typically all correlated, and this correlation has to be properly accounted for in the statistical analyses. In the present paper, the focus is on the setting where normative data have to be established for multi-trial memory tests. At present, normative data for such tests are typically based on a series of univariate analyses, i.e. a statistical model is fitted for each of the test scores separately. This approach is suboptimal because (1) the correlated nature of the data is not accounted for, (2) multiple testing issues may arise, and (3) the analysis is not parsimonious.
  
  
  RESULTS
  Here, a normative approach that is not hampered by these issues is proposed (the so-called multivariate regression-based approach). The methodology is exemplified in a sample of N = 221 Dutch-speaking children (aged between 5.82 and 15.49 years) who were administered Rey's Auditory Verbal Learning Test. An online Appendix that details how the analyses can be conducted in practice (using the R software) is also provided.
  
  
  CONCLUSIONS
  The multivariate normative regression-based approach has some substantial methodological advantages over univariate regression-based methods. In addition, the method allows for testing substantive hypotheses that cannot be addressed in a univariate framework (e.g. trial by covariate interactions can be modeled).
authors.affiliation: a Statistical & Decisions Sciences - Quantitative Sciences , The Janssen Pharmaceutical Companies of Johnson & Johnson , Beerse , Belgium.|b Center for Statistics (CenStat), KU Leuven & UHasselt , Diepenbeek , Belgium.
authors.forename: Wim
authors.initials: W
authors.lastname: Van der Elst
authors.affiliation: b Center for Statistics (CenStat), KU Leuven & UHasselt , Diepenbeek , Belgium.
authors.forename: Geert
authors.initials: G
authors.lastname: Molenberghs
authors.affiliation: c Centre for Brain & Learning, Faculty of Behavioral and Movement Sciences , Vrije Universiteit Amsterdam , Amsterdam , The Netherlands.
authors.forename: Marleen
authors.initials: M
authors.lastname: van Tetering
authors.affiliation: c Centre for Brain & Learning, Faculty of Behavioral and Movement Sciences , Vrije Universiteit Amsterdam , Amsterdam , The Netherlands.
authors.forename: Jelle
authors.initials: J
authors.lastname: Jolles
mesh_terms: D000293:Adolescent; D002648:Child; D005260:Female; D006801:Humans; D008297:Male; D008568:Memory; D015999:Multivariate Analysis; D009483:Neuropsychological Tests / Q000592:standards*; D012044:Regression Analysis
keywords: Multivariate regression; Rey’s Verbal Learning Test; correlated test scores; norms