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Niki Su posted on Sunday, December 17, 2017  6:37 pm



There is a XM1M2Y twostep mediating model, and all are level1 variables. The indirect effect should be a1a2a3+ca1ca2+ca2a3+ca1a3? model: %within% sa1M1 on X; sa2M2 on M1; sa3Y on M2; scY on X; %between% [sa1](a1); [sa2](a2); [sa3](a3); sa1 with sa2(ca1a2); sa3 with sa2(ca2a3); sa1 with sa3(ca1a3); 


You need to derive the expectation of the product of the 3 random slopes to check. 

Niki Su posted on Tuesday, December 19, 2017  11:37 pm



Thank you very much. But maybe I didn't describe the question clearly. In a 111 model, the indirect effect should be the product of 2 random slopes plus their covariance. But when it is a 1111 model, I don't know how to deal with the covariance. Back to the 1111 model described initially, should the indirect effect be the product of the 3 random slopes plus covariances of each two of the 3 random slopes? 


Yes, that's what I understood you to say. I suggested that you derive this indirect effect (by starting with the expectation of the 3 random variables). 


Ok, I derived it for you. You may want to check it, but here is what I get  in your notation the indirect effect should be a1*a2*a3+ca1a2*a3+ca2a3*a1+ca1a3*a3 

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