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. Author manuscript; available in PMC: 2017 Jun 22.
Published in final edited form as: J Stat Theory Pract. 2016 Jun 22;10(3):574–587. doi: 10.1080/15598608.2016.1203843

Table 1.

Simulation statistics of the estimated natural indirect effect for a continuous exposure and a dichotomous outcome, n = 200.

Scenario True Y Model True M Model Risk Difference, IE(x)RD (%)
Odds Ratio, log(IE(x)OR)
True IE Ave Est IE Ave PE (%) SD of Est IE AVE SE CP (%) True log(IE) Ave Est log(IE) Ave PE (%) SD of Est log(IE) AVE SE CP (%)


Binary Mediator
1 Logit Logit 1.07 1.09 1.7 0.67 0.66 91.1 0.068 0.069 2.1 0.041 0.040 91.1
2 Logit Probit 0.81 0.84 4.4 0.61 0.59 92.7 0.051 0.053 3.8 0.037 0.036 92.8
3 Probit Logit 0.74 0.78 5.2 0.57 0.56 91.1 0.047 0.049 4.6 0.035 0.035 91.9
4 Probit Probit 0.82 0.86 5.8 0.60 0.60 93.6 0.052 0.054 4.1 0.036 0.037 93.6
Continuous Mediator
5 Logit Lin 0.85 0.83 −2.0 0.50 0.51 91.5 0.046 0.046 −1.0 0.027 0.028 92.6
6 Logit Mix 0.71 0.64 −9.1 0.53 0.52 92.5 0.038 0.034 −8.8 0.028 0.027 92.9
7 Probit Lin 0.88 0.92 5.6 0.57 0.54 93.0 0.049 0.052 5.9 0.031 0.030 93.3
8 Probit Mix 0.87 0.81 −7.4 0.64 0.64 93.1 0.042 0.039 −7.4 0.030 0.030 93.7

Lin, a linear regression model for the continuous mediator M with normally distributed residuals; Mix, a Gaussian mixture model for the continuous mediator M with a weighted sum of two Gaussian component densities.