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| Niki Su posted on Sunday, December 17, 2017 - 6:37 pm
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There is a X-M1-M2-Y two-step mediating model, and all are level-1 variables.
The indirect effect should be a1a2a3+ca1ca2+ca2a3+ca1a3?
model:
%within%
sa1|M1 on X;
sa2|M2 on M1;
sa3|Y on M2;
sc|Y on X;
%between%
[sa1](a1);
[sa2](a2);
[sa3](a3);
sa1 with sa2(ca1a2);
sa3 with sa2(ca2a3);
sa1 with sa3(ca1a3); |
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| You need to derive the expectation of the product of the 3 random slopes to check. |
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| Niki Su posted on Tuesday, December 19, 2017 - 11:37 pm
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| Thank you very much. But maybe I didn't describe the question clearly. In a 1-1-1 model, the indirect effect should be the product of 2 random slopes plus their covariance. But when it is a 1-1-1-1 model, I don't know how to deal with the covariance. Back to the 1-1-1-1 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? |
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| 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). |
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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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