A General Model for Testing Mediation and Moderation Effects

Department of Psychology, University of South Carolina, Barnwell College, 1512 Pendleton St., Columbia, SC 29208, USA.
Prevention Science (Impact Factor: 2.63). 12/2008; 10(2):87-99. DOI: 10.1007/s11121-008-0109-6
Source: PubMed

ABSTRACT This paper describes methods for testing mediation and moderation effects in a dataset, both together and separately. Investigations of this kind are especially valuable in prevention research to obtain information on the process by which a program achieves its effects and whether the program is effective for subgroups of individuals. A general model that simultaneously estimates mediation and moderation effects is presented, and the utility of combining the effects into a single model is described. Possible effects of interest in the model are explained, as are statistical methods to assess these effects. The methods are further illustrated in a hypothetical prevention program example.

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    • "In other to improve the efficiency of MMR technique, Anderson et al (1996) recommended the use of small sample size Cortina (1993) recommended the use of square terms as covariates. Fairchild and MacKinnon (2009) wrote on a general model that has the capability of estimating both mediation and moderation effects simultaneously. "
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    ABSTRACT: The paper introduces the concept of reverse moderation in order to investigate the uniqueness of the coefficients of independent variables and non-commutative nature of interactions in moderated multiple regression (MMR) in hierarchical order. The moderation effect is 0.01and the data used was masked to maintain the integrity of an ongoing research. The research concludes that moderation and its reverse yield different results indicating the uniqueness of the coefficients of the independent variables and the interactions are not commutative. Interactions are one-way. Each case is different as shown by the results of the 20 models used.
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    • "The product of coefficients method for testing statistical mediation was applied using MPlus Version 5.2 (Muthén & Muthén, Los Angeles, LA), with percentile bootstrapping implemented to adjust asymmetric confidence limits and address biased standard errors (Fairchild, Mackinnon, Taborga, & Taylor, 2009; MacKinnon, Lockwood, Hoffman, West, & Sheets, 2002). This method provides a balance of power and Type I error and supports the use of mediation when there may not be strong predictoreoutcome associations , whereas the causal steps and difference in coefficients methods are less advisable for relatively smaller samples, and are more susceptible to Type II errors (Fairchild & MacKinnon, 2009; Fritz & MacKinnon, 2007; MacKinnon et al., 2002). The product of coefficients method involves regression of outcomes on the mediator and predictors, and regression of the mediator on the predictors , yielding two coefficients that link predictors to the mediator and the mediator to the outcome, with the product of these coefficients providing an estimate of the mediated/indirect effect (ab). "
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    • "We also expected that promoting prosocial behavior could result in an improvement of academic achievement in accordance with previous findings highlighting the long-term effect of prosociality on academic achievement (Caprara et al. 2000). Finally, in line with the prevention research and its implications for mental health interventions (Fairchild and Mackinnon 2009), we investigated the presence of moderation effects among participants in responding to CEPIDEA as well as possible mediation mechanisms through which CEPIDEA could have achieved its effects (i.e., the impact of prosocial behaviors on the reduction of aggressive behaviors; see Caprara et al. 2014). Overall, in pursuing the enhancement of prosocial behaviors in the classroom, CEPIDEA paid close attention to its impact on peer relationships using peer ratings to assess the changes in behavior (prosocial behavior and aggression ) due to the intervention condition. "
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    ABSTRACT: Prosocial behaviors are considered integral to intervention goals that seek to promote successful youth development. This study examines the effect of a school-based intervention program entirely designed to promote prosocial behaviors called Promoting Prosocial and Emotional Skills to Counteract Externalizing Problems in Adolescence (Italian acronym CEPIDEA). The CEPIDEA curriculum was incorporated into routine educational practices and included five major components that reflect the personal determinants of prosocial behavior during adolescence. The present study assessed 151 students (48.7 % female; M age = 12.4) of the intervention school and 140 students (51.2 % female; M age = 13.0) of the control school at three points. A multi-group latent curve analysis revealed that the intervention group, compared with the control group, showed an increase in prosocial behavior, interpersonal self-efficacy beliefs, and agreeableness along with a decrease in physical aggression above and beyond the normative developmental trend of the these variables. Participants of the intervention also obtained higher grades than the control group at the end of middle school. Moderation effects for prosocial behavior and agreeableness evidenced that those who benefited most from the intervention were those adolescents with lower normative development of prosocial behavior, low initial level of agreeableness, and high initial level of physical aggression. The results also showed that the increase of prosocial behaviors mediated the decline of verbal aggression in adolescents who had attended the intervention. These findings suggest that interventions aimed at promoting prosocial behaviors while having the potential to support positive outcomes may also counteract or redirect negative trajectories of functioning.
    Journal of Youth and Adolescence 05/2015; DOI:10.1007/s10964-015-0293-1 · 2.72 Impact Factor
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