Mediation analysis with categorical independent variables. (1st January 2012)

• Record Type: Journal Article
• Authors: Kang, Hyoung-Kil; Lee, Eunsoon
• Is Part Of: International journal of experimental design and process optimisation. Volume 3:Number 2(2012)
• Page Start: 178
• Page End: 197
• Publication Date: 2012-01-01
• Subjects: categorical independent variables -- dummy coding -- relative indirect effect -- relative total effect -- reference category; Experimental design -- Periodicals; Process control -- Statistical methods -- Periodicals; 620.0072
• Languages: English
• ISSNs: 2040-2252

Abstract

The primary goal of mediation analysis is to explicate the mechanism that underlies an observed relationship between an independent variable and a dependent variable by including a third explanatory variable, known as a mediator variable. While the concept of mediation is theoretically appealing, our literature study indicates that there has not been a comprehensive research work on how a categorical variable is assessed in the statistical mediation analysis of time and perceived quality of life. The main objective of this paper is two-fold. First, this paper develops conceptual justifications of employing psychological variables to represent unique constructs with as little conceptual overlap as possible in the mediation analysis to prevent multicollinearity issues. Second, a modified approach is then proposed to estimate relative direct and indirect effects as well as relative total effects between a categorical independent variable and a dependent variable. A numerical example is provided to facilitate the proposed approach.