《Lower level mediation in multilevel models》.pdf

Psychological Methods Copyright 2003 by the American Psychological Association, Inc. 2003, Vol. 8, No. 2, 115–128 1082-989X/03/$12.00 DOI: 10.1037/1082-989X.8.2.115 Lower Level Mediation in Multilevel Models David A. Kenny and Niall Bolger Josephine D. Korchmaros New York University University of Connecticut Multilevel models are increasingly used to estimate models for hierarchical and repeated measures data. The authors discuss a model in which there is mediation at the lower level and the mediational links vary randomly across upper level units. One repeated measures example is a case in which a person’s daily stressors affect his or her coping efforts, which affect his or her mood, and both links vary ran- domly across persons. Where there is mediation at the lower level and the media- tional links vary randomly across upper level units, the formulas for the indirect effect and its standard error must be modified to include the covariance between the random effects. Because no standard method can estimate such a model, the authors developed an ad hoc method that is illustrated with real and simulated data. Limi- tations of this method and characteristics of an ideal method are discussed. Multilevel models for hierarchical and repeated ample, schools are the groups, and schoolchildren are measures data are becoming increas