I would like to do a mediation analysis. The variables involved are treatment for infertility (0/1), Gestational age (22-40 weeks) and Birthweight (500- 6000 grams).
I have done a preliminary mediation analysis based on regression method. Since gestational age and birthweight are continuous, I used linear regression. I am not sure whether the analysis is correct or not.
Looking for your advice . Thank you very much
Research Question: is the relationship between treatment (trt) for infertility and birthweight (Bwt) mediated through gestational age (GA)
ie Trt ------------------------> GA ----------------------> Bwt
Regression method:
Regress Bwt = 18.5 * trt + 3244.16
Regress GA = -0.1055 * trt + 38.92
Regress Bwt = 37.19 * trt + 177.18 * GA – 3651.94
Direct effect = 37.19
Indirect effect = -0.1055 * 177.18 = -18.69
Total effect = 37.19 -18.69 = 18.5
Proportion of mediated effect = Indirect effect / Total effect
= -18.69 /18.5
I have done a preliminary mediation analysis based on regression method. Since gestational age and birthweight are continuous, I used linear regression. I am not sure whether the analysis is correct or not.
Looking for your advice . Thank you very much
Research Question: is the relationship between treatment (trt) for infertility and birthweight (Bwt) mediated through gestational age (GA)
ie Trt ------------------------> GA ----------------------> Bwt
Regression method:
Regress Bwt = 18.5 * trt + 3244.16
Regress GA = -0.1055 * trt + 38.92
Regress Bwt = 37.19 * trt + 177.18 * GA – 3651.94
Direct effect = 37.19
Indirect effect = -0.1055 * 177.18 = -18.69
Total effect = 37.19 -18.69 = 18.5
Proportion of mediated effect = Indirect effect / Total effect
= -18.69 /18.5
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