st: Re: advice re: "intervening" variable

["Sergiy Radyakin" <Radyakin@aoek.uni-hannover.de>]

Hello Richard,

Google picture search --> "structural model" will give you a lot of 
examples.
However "intervening" variable is the one which usually reflects a Concept, 
like "hunger" or "fear" (lots of examples from the area of psychology).

E.g. here you will find a model of impulse-buying behaviour:
http://emeraldinsight.com/Insight/ViewContentServlet?Filename=Published/EmeraldFullTextArticle/Articles/2840100404.html

While "Fashion involvment" and "Impulse buying" are quite real, "positive 
emotion" is rather hypothesized.

Your "diameter of blood vessel" seems to be quite a real variable though.
I am not a doctor, but I thought it works the other way around:
one smokes --> diameter decreases --> pressure increases --> heart rate 
increases --> one dies ?

Another chain:
"Moreover, The nicotine in cigarettes and other tobacco products causes your 
blood vessels to constrict and your heart to beat faster, which temporarily 
raises your blood pressure. "
is described here: 
http://www.highbloodpressuremed.com/smoking-and-high-blood-pressure.html

I wonder how do you establish causality in this case?

----
An example from economics (Student Achievement and National Economic
Growth, Nov 2006): 
http://www.journals.uchicago.edu/AJE/journal/issues/v113n1/113101/113101.web.pdf


Regards, Sergiy



----- Original Message ----- 
From: "Richard Goldstein" <richgold@ix.netcom.com>
To: "statalist" <statalist@hsphsun2.harvard.edu>
Sent: Monday, March 05, 2007 3:57 PM
Subject: st: advice re: "intervening" variable



> Hi all:
>
> This is more a stat question that a Stata question.
>
> I have a system of 3 variables where one variable is in between,
> in time and physiology, the other two variables:
>
> blood pressure -> diameter of blood vessel -> heart rate
>
> That is, a change in blood pressure "causes" some change in
> the diameter of the blood vessel which in turn "causes"
> some change in heart rate (actually in "RRI" which is,
> basically, the inverse of heart rate).
>
> I have never come across this situation before, but I believe
> that several substantive disciplines do have such situations.
>
> Actually, I have found a fair amount of literature in
> psychology; a recent overview is MacKinnon, DP, AJ Fairchild,
> and MS Fritz (2007), "Mediation Analysis", _Annual Review of
> Psychology_, 58: 593-614
>
> I believe that other disciplines might also see such
> situations, e.g., economics and epidemiology, but have
> been unable to find any literature.
>
> So, is there literature on this in disciplines other than
> psychology? If so, any citations, esp. overviews, would
> be greatly appreciated (regardless of whether the cite is
> to ariticles or books).
>
> Thanks,
>
> Rich
>
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