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. 2013 Jan-Feb;62(1):45-9.
doi: 10.1097/NNR.0b013e3182741948.

Composite variables: when and how

Mi-Kyung Song  1 , Feng-Chang Lin, Sandra E Ward, Jason P Fine
Affiliations

Composite variables: when and how

Mi-Kyung Song et al. Nurs Res. 2013 Jan-Feb.

Abstract

Background: Use of composite variables is a common practice, but knowledge about what researchers should consider when creating composite variables is lacking.

Objective: The purpose of this paper was to present methods used to create composite variables with attention to advantages and disadvantages.

Methods: Methods of simple averaging, weighted averaging, and meaningful grouping to create composite variables are described briefly, and the context in which one method might be more suitable than the others is discussed. Study examples and comparisons of statistical power among these methods as well as Bonferroni correction are described.

Discussion: Each approach to creating composite variables has advantages and disadvantages that researchers should weigh carefully. With normally distributed data, composite variables provide the greatest increases in power when the original variables (that make up the composite variable) have similar associations with the outside outcome variable.

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Conflict of interest statement

The authors have no conflicts of interest to disclose.

Figures

FIGURE 1
FIGURE 1
Power comparisons when n = 50, a = 0.05, and ρx1y = ρx2y = ρx3y.
FIGURE 2
FIGURE 2
Power comparisons when n = 50, a = 0.05, and ρx2y = ρx3y = 0.
See this image and copyright information in PMC

References

    1. Daut RL, Cleeland CS, Flanery RC. Development of the Wisconsin Brief Pain Questionnaire to assess pain in cancer and other diseases. Pain. 1983;17:197–210. - PubMed
    1. De Pauw SS, Mervielde I, De Clercq BJ, De Fruyt F, Tremmery S, Deboutte D. Personality symptoms and self-esteem as correlates of psychopathology in child psychiatric patients: Evaluating multiple informant data. Child Psychiatry and Human Development. 2009;40:499–515. - PubMed
    1. Dillon WR, Goldstein M. Multivariate analysis: Methods and applications. New York, NY: John Wiley & Sons; 1984.
    1. Freemantle N, Calvert M, Wood J, Eastaugh J, Griffin C. Composite outcomes in randomized trials: Greater precision but with greater uncertainty? JAMA. 2003;289:2554–2559. - PubMed
    1. Ley P. Quantitative aspects of psychological assessment. London, UK: Gerald Duckworth & Co; 1972.

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