⼀⽂读懂中介效应之sgmediation操作
1
Sobel-Goodman mediation tests
Deion：
The purpo of the Sobel-Goodman tests are to test whether a mediator carries the influence of an IV to a DV. A variable may be considered a mediator to the extent to which it carries the influence of a given independent variable (IV) to a given dependent variable (DV). Generally speaking, mediation can be said to occur when (1) the IV significantly affects the mediator, (2) the IV significantly affects the DV in the abnce of the mediator, (3) the mediator has a significant unique effect on the DV, and (4) the effect of the IV on the DV shrinks upon the addition of the mediator to the model.
水稻生长过程>抽象危险犯语法格式为：
sgmediation 因变量, mv(中介变量) iv(⾃变量) cv(控制变量 )
•
吴中四才子sgmediationdepvar[if exp][in range], mv:(mediatorvar)iv(indvar) [ cv(covarlist) quietly ]
好大王碑选项含义为：
cv(covarlist) Optional list of covariate variables.
阳光依旧灿烂
quietly Suppress the individual regression output.
2
操作案例
本例使⽤hsbdemo数据集，其中science作为DV, math作为IV, read作为中介变量。也就是说，模型说数学影响阅读，⽽阅读反过来⼜影响科学。这个模型可能有也可能没有太⼤的实际意义，但是它将允许我们演⽰运⾏⼀个中介效应测试的过程。我们将使⽤sgmediation command来完成这个任务，您可以使⽤findit sgmediation来下载这个命令。
该数据包括200个学⽣的选择的项⽬类型(prog，三种类型 categorical variable), 他们的社会地位（s 三种地位categorical variable），写作分数（write， a continuous variable）。
属羊的出生年份导⼊数据，然后进⾏查看数据
•
•
edit desc
数据如下：
进⾏操作为：
•
sgmediation science, mv(read) iv(math)
sgmediation science, mv(read) iv(math)
In this example the mediation effect of read was statistically significant with approximately 40% of the total effect (of math onscience) being mediated.
在这个例⼦中，read的中介效果在统计上是显著的，⼤约40%的总效果(数学对科学)是被中介的。
简爱读书报告
3
操作案例
•
sgmediation science, mv(read) iv(math) cv(write)
4
操作案例
bootstrap with ca resampling
•
•
bootstrap r(ind_eff) r(dir_eff), reps(1000): sgmediation science, mv(read) iv(math) estat bootstrap, percentile bc
If you prefer to do a residual resampling bootstrap rather than ca resampling bootstrap, you can u the resboot-mediationcommand (findit resboot_mediation).
bootstrap with residual resampling need to install resboot_mediation
•
•
findit resboot_mediaton resboot_mediation, dv(science) mv(read) iv(math) reps(1000)
5
References
Aroian, L.A. (1944). The probability function of the product of two normally distributed variables. Annals of
Mathematical Statistics, 18, 265-271.
Baron, R.M. & Kenny, D.A. (1986), Moderator-Mediator Variables Distinction in Social Psychological Rearch: Conceptual, Strategic, and Statistical Considerations. Journal of Personality and Social Psychology, 51 (6), 1173–82. Goodman, L.A. (1960) On the exact variance of products. Journal of th
e American Statistical Association, 55, 708-713. MacKinnon, D. P. & Dwyer, J. H. (1993). Estimating mediated effects in prevention studies. Evaluation Review, 17, 144-158.
MacKinnon, D. P., Warsi, G., & Dwyer, J. H. (1995). A simulation study of mediated effect measures. Multivariate Behavioral Rearch, 30(1), 41-62.
Preacher, K. J. & Hayes, A. F. (2004). SPSS and SAS procedures for estimating indirect effects in simple mediation models. Behavior Rearch Methods, Instruments, & Computers, 36(4), 717-731.
Sobel, M.E. (1982) Asymptotic confidence intervals for indirect effects in structural equation models. Sociological Methodology, 13, 290-312.
Sobel, M.E. (1986) Some new results on indirect effects and their standard errors in covariance structure models. Sociological Methodology, 16, 159-186.
Stata寒假研讨班_2020年1⽉15⽇——1⽉18⽇_第14届“⾼级计量经济学及stata应⽤”研讨班@北京专场
新年祝福语四字顺口溜
