A SIMULATION STUDY OF MEDIATED EFFECT MEASURES
A SIMULATION STUDY OF MEDIATED EFFECT MEASURES
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DOI：
10.1207/s15327906mbr3001_3
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发表时间：
1995-01-01
影响因子：
3.8
通讯作者：
DWYER, JH
中科院分区：
文献类型：
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作者：
MACKINNON, DP;WARSI, G;DWYER, JH
通过统计模拟研究了中介效应的点和方差估计量、中介效应与直接效应的比率以及中介效应占总效应的比例的解析解。我们将基于多元 delta 方法和二阶泰勒级数展开的几种近似解与每个估计量的经验标准差和可用的理论标准误差进行了比较。模拟包括 8 个样本量（N = 10、25、50、100、500、1000 和 5000）和 64 个参数值组合的三个正态分布变量的 500 次重复。对于至少 50 个样本量，间接效应标准误差的不同解非常相似，除非自变量被二分。准确估计中介比例的点和方差需要至少 500 个样本量。直到所有连续变量情况的样本量达到 2,000 时，介导效应与非介导效应之比的点和方差估计才稳定。讨论了实验和非实验研究中介导效应估计的含义。
Analytical solutions for point and variance estimators of the mediated effect, the ratio of the mediated to the direct effect, and the proportion of the total effect that is mediated were studied with statistical simulations. We compared several approximate solutions based on the multivariate delta method and second order Taylor series expansions to the empirical standard deviation of each estimator and theoretical standard error when available. The simulations consisted of 500 replications of three normally distributed variables for eight sample sizes (N = 10, 25, 50, 100, 500, 1000, and 5000) and 64 parameter value combinations. The different solutions for the standard error of the indirect effect were very similar for sample size of at least 50, except when the independent variable was dichotomized. A sample size of at least 500 was needed for accurate point and variance estimates of the proportion mediated. The point and variance estimates of the ratio of the mediated to nonmediated effect did not stabilize until the sample size was 2,000 for the all continuous variable case. Implications for the estimation of mediated effects in experimental and nonexperimental studies are discussed.