Re: Double mediation

2001-07-06 Thread Duncan Smith


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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Double mediation

2001-07-05 Thread Sylvia J. Hysong, Ph.D.

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.


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