A critical review of scoring options for clinical measurement tools.
BACKGROUND
The aim of this paper is twofold: (1) to describe the fundamental differences between formative and reflective measurement models, and (2) to review the options proposed in the literature to obtain overall instrument summary scores, with a particular focus on formative models.


METHODS
An extensive literature search was conducted using the following databases: MEDLINE, EMBASE, PsycINFO, CINAHL and ABI/INFORM, using "formative" and "reflective" as text words; relevant articles' reference lists were hand searched.


RESULTS
Reflective models are most frequently scored by means of simple summation, which is consistent with the theory underlying these models. However, our review suggests that formative models might be better summarized using weighted combinations of indicators, since each indicator captures unique features of the underlying construct. For this purpose, indicator weights have been obtained using choice-based, statistical, researcher-based, and combined approaches.


CONCLUSIONS
Whereas simple summation is a theoretically justified scoring system for reflective measurement models, formative measures likely benefit from the use of weighted scores that preserve the contribution of each of the aspects of the construct.
Department of Pediatrics, The Hospital for Sick Children, University of Toronto, Toronto, Ontario, Canada. laura.avila@sickkids.ca.
Maria Laura
ML
Avila
Lawrence S. Bloomberg Faculty of Nursing, University of Toronto, Toronto, Ontario, Canada. jennifer.stinson@sickkids.ca.|Child Health Evaluative Sciences, The Hospital for Sick Children, University of Toronto, Toronto, Ontario, Canada. jennifer.stinson@sickkids.ca.
Jennifer
J
Stinson
Department of Research Design and Biostatistics, Institute for Clinical Evaluative Sciences, Sunnybrook Health Sciences Centre, Toronto, Ontario, Canada. alex.kiss@ices.on.ca.
Alex
A
Kiss
Department of Pediatrics, The Hospital for Sick Children, University of Toronto, Toronto, Ontario, Canada. leonardo.brandao@sickkids.ca.
Leonardo R
LR
Brandão
Department of Pediatrics, The Hospital for Sick Children, University of Toronto, Toronto, Ontario, Canada. jasnagora@rogers.ca.
Elizabeth
E
Uleryk
Department of Pediatrics, The Hospital for Sick Children, University of Toronto, Toronto, Ontario, Canada. brian.feldman@sickkids.ca.|Child Health Evaluative Sciences, The Hospital for Sick Children, University of Toronto, Toronto, Ontario, Canada. brian.feldman@sickkids.ca.
Brian M
BM
Feldman
D015984:Causality; D006305:Health Status Indicators; D006801:Humans; D016015:Logistic Models; D011594:Psychometrics; D012107:Research Design; D012660:Semantics; D009626:Terminology as Topic