关于部分中介与完全中介作用(与课堂定义相同).doc

?q=cache:IERvvryqTfQJ:/cm/+what+is+ partial+mediation&hl=&ct=clnk&cd=6&&st_usg=ALhdy28nm9ic9hiZ2WRtEodqzcd -ciATMw 来源: google 网页快照 David A. Kenny January 10, 2008 Please email me suggestions and corrections . MEDIATION What is Mediation ?Baron &Kenny Steps Measuring Mediation orthe Indirect Effect Design Issues Specification Error Extensions Links toOther Sites References What Is Mediation ? Consider a variable X that is assumed to affect another variable Y. The variable X is called the initial variable and the variable that it causes orY is called the e . In diagrammatic form, the unmediated model is图片显示不出来 The effect ofX on Y may be mediated by a process or mediating variable M, and the variable X may still affect Y. Path c is called the total effect . The mediated model is图片显示不出来(These two diagrams are essential to the understanding of this page. Please study them carefully!) Path c' is called the direct effect . The mediator has been called an intervening or process variable. Complete mediation is the case in which variable X no longer affects Y after M has been controlled and so path c' is zero. Partial mediation is the case in which the path from X toY is reduced in absolute size but is still different from zero when the mediator is controlled. Note that a mediational model isa causal model. For example, the mediator is presumed to cause the e and not vice versa. If the presumed model is not correct, the results from the mediational analysis are of little value. Mediation is not defined statistically; rather statistics can be used to evaluate a presumed mediational model. The reader should consult the section below on Specification Error . There isa long history in the study of mediation (Hyman, 1955; orquodale & Meehl, 1948). Currently mediation isa very popular topic. (This page averages over 100 different visitors a day.) There are several reasons for the intense interest in this topic. One reason for testing mediation