Incorporating nonlinearity into mediation analyses

Public Deposited
Analytics

Downloadable Content

Download PDF
Request Version for Screen Reader
Creator
  • Knafl, George
    • Affiliation: School of Nursing
  • Knafl, Kathleen
    • Affiliation: School of Nursing
  • Grey, Margaret
    • Other Affiliation: School of Nursing, Yale University, New Haven, USA
  • Dixon, Jane
    • Other Affiliation: School of Nursing, Yale University, New Haven, USA
  • Deatrick, Janet A
    • Other Affiliation: School of Nursing, University of Pennsylvania, Philadelphia, USA
  • Gallo, Agatha M
    • Other Affiliation: College of Nursing, University of Illinois at Chicago, Chicago, USA
Abstract
  • Background Mediation is an important issue considered in the behavioral, medical, and social sciences. It addresses situations where the effect of a predictor variable X on an outcome variable Y is explained to some extent by an intervening, mediator variable M. Methods for addressing mediation have been available for some time. While these methods continue to undergo refinement, the relationships underlying mediation are commonly treated as linear in the outcome Y, the predictor X, and the mediator M. These relationships, however, can be nonlinear. Methods are needed for assessing when mediation relationships can be treated as linear and for estimating them when they are nonlinear. Methods Existing adaptive regression methods based on fractional polynomials are extended here to address nonlinearity in mediation relationships, but assuming those relationships are monotonic as would be consistent with theories about directionality of such relationships. Results Example monotonic mediation analyses are provided assessing linear and monotonic mediation of the effect of family functioning (X) on a child’s adaptation (Y) to a chronic condition by the difficulty (M) for the family in managing the child's condition. Example moderated monotonic mediation and simulation analyses are also presented. Conclusions Adaptive methods provide an effective way to incorporate possibly nonlinear monotonicity into mediation relationships.
Date of publication
DOI
Identifier
Resource type
  • Article
Rights statement
  • In Copyright
Rights holder
  • The Author(s).
Journal title
  • BMC Medical Research Methodology
Journal volume
  • 17
Journal issue
  • 1
Page start
  • 45
Language
  • English
Bibliographic citation
  • BMC Medical Research Methodology. 2017 Mar 21;17(1):45
Publisher
  • BioMed Central

Relations

Parents:

This work has no parents.

Items

Thumbnail Title Date Uploaded Visibility Actions
file details 12874_2017_article_296.pdf 2019-05-06 Public Download