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sgmediation y, mv(m) iv(x) cv(c)。
制变量,sgmediation y, mv(m) iv(x) cv(c)。具体结果如下:
. sgmediation perform, mv(satis) iv(support) //用 sobel 方法检验中介变量
Model with dv regressed on iv (path c) //这里,Stata 自动检验经理激励和员工工作表现之间的路径,形成路径 c
Source | SS df MS Number of obs = 1500
-------------+------------------------------ F( 1, 1498) = 412.00
Model | 258.999482 1 258.999482 Prob > F = 0.0000
Residual | 941.695489 1498 .628635173 R-squared = 0.2157
-------------+------------------------------ Adj R-squared = 0.2152
Total | 1200.69497 1499 .800997312 Root MSE = .79287
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perform | Coef. Std. Err. t P>|t| [95% Conf. Interval]
-------------+----------------------------------------------------------------
support | .8217557 .0404849 20.30 0.000 .7423427 .9011687
_cons | 4.99836 .0204746 244.13 0.000 4.958198 5.038522
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Model with mediator regressed on iv (path a) //这里,Stata 检验中介变量 (工作满意度) 与自变量 (经理激励) 之间的关系,形成路劲 a
Source | SS df MS Number of obs = 1500
-------------+------------------------------ F( 1, 1498) = 56.23
Model | 20.0948214 1 20.0948214 Prob > F = 0.0000
Residual | 535.351023 1498 .357377185 R-squared = 0.0362
-------------+------------------------------ Adj R-squared = 0.0355
Total | 555.445844 1499 .370544259 Root MSE = .59781
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satis | Coef. Std. Err. t P>|t| [95% Conf. Interval]
-------------+----------------------------------------------------------------
support | .2288945 .0305251 7.50 0.000 .1690181 .2887709
_cons | .019262 .0154376 1.25 0.212 -.0110195 .0495436
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Model with dv regressed on mediator and iv (paths b and c') //加入中介变量, Stata 再次检验经理支持对员工工作表现的影响
Source | SS df MS Number of obs = 1500
-------------+------------------------------ F( 2, 1497) = 1015.21
Model | 691.131957 2 345.565979 Prob > F = 0.0000
Residual | 509.563014 1497 .340389455 R-squared = 0.5756
-------------+------------------------------ Adj R-squared = 0.5750
Total | 1200.69497 1499 .800997312 Root MSE = .58343
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perform | Coef. Std. Err. t P>|t| [95% Conf. Interval]
-------------+----------------------------------------------------------------
satis | .8984401 .0252156 35.63 0.000 .8489785 .9479017
support | .6161077 .0303447 20.30 0.000 .556585 .6756303
_cons | 4.981054 .015074 330.44 0.000 4.951486 5.010622
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Sobel-Goodman Mediation Tests //进行 Sobel 检验,原假设 $H0 : ab=0$
Coef Std Err Z P>|Z|
Sobel .20564799 .02802571 7.338 2.172e-13 //我们需要关注这个部分的 P 值,这里的 P<0.05 则代表拒绝原假设,中介效应成立
Goodman-1 (Aroian) .20564799 .02803628 7.335 2.216e-13
Goodman-2 .20564799 .02801514 7.341 2.127e-13
Coef Std Err Z P>|Z|
a coefficient = .228894 .030525 7.49857 6.5e-14 // 这里分别提供了输入命令三个变量之间的关系路径系数
b coefficient = .89844 .025216 35.6304 0
Indirect effect = .205648 .028026 7.33783 2.2e-13
Direct effect = .616108 .030345 20.3036 0
Total effect = .821756 .040485 20.2979 0
Proportion of total effect that is mediated: .25025442 //这里 Stata 直接帮我们计算出中介效应在总效应中的占比 25.03%
Ratio of indirect to direct effect: .3337858
Ratio of total to direct effect: 1.3337858
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完整结果解读
经理激励对员工工作表现的总效应,等于直接效应 0.616 加上 间接效应 0.206,总效应为 0.822;
中介效应的 Sobel 检验 P 值小于 0.05,说明中介效应成立;
计算出的中介效应在总效应中占比为 25.03%。
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