Sylvia J. Hysong, Ph.D. <[EMAIL PROTECTED]> wrote in message
[EMAIL PROTECTED]">news:[EMAIL PROTECTED]...
> Hello,
>
> I'm hoping someone can help me with this. I have looked at a
> multitude of resources including the David Kenny page, this and other
> newsgroups, Pedhazur (1982), Cohen & Cohen (1983), and Darlington
> (1990?), to no avail. I am hoping someone can direct me to the right
> resource. I am trying to conduct a test of double mediation. In
> other words, I am trying to test the hypothesis that x-->z1-->z2-->y.
> Is there a way to do this (and if so, what is it?), or must I result
> to a path analysis or a structural equation model?
>
> Thanks in advance for any help.
If I understand the question correctly, this implies a number of conditional
independence relationships which can be tested. i.e. x cond. ind. of z2 and
y given z1; x and z1 cond. ind. of y given z2; x cond. ind. of y given z1
and z2. If these, and only these, independence relationships hold then you
have either x-->z1-->z2-->y or x<--z1<--z2<--y. To decide which, you need
some background knowledge or to conduct an experiment. You might want to
check out links at http://www.cs.berkeley.edu/~murphyk/Bayes/bnsoft.html
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