[Mediation-information] request

dustin tingley dtingley at gov.harvard.edu
Wed Aug 29 15:47:34 CEST 2012


Hi Murthy-

I recommend using the medsens function on output from mediate, not
mediations. This will make things simpler for you.

best,
Dustin

Dustin Tingley
Government Department
Harvard University
http://scholar.harvard.edu/dtingley
Director, Program on Experience Based Learning in the Social Sciences
http://projects.iq.harvard.edu/peblss/
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On Tue, Aug 28, 2012 at 12:14 AM, Kosuke Imai <kimai at princeton.edu> wrote:

> Thanks for your message. I'm ccing my coauthors who know the details of
> the software and might be able to give you some suggestions.
>
> Kosuke
>
> Department of Politics
> Princeton University
> http://imai.princeton.edu
>
> On Aug 27, 2012, at 8:26 PM, Murthy Mittinty wrote:
>
> > Dear Prof. K Imai,
> >
> > Myself am Murthy. N. Mittinty, working as post doctoral fellow at the
> School of Population Health, in University of Adelaide. In my research I
> had found that use of Causal mediation analysis answers the research
> question that I am interested in. It is in this regard I tried using the
> Causal mediation analysis software developed by you and your colleagues in
> R. I have understood the output and the maths behind the programs through
> the references. I thank you very much for developing this software.
> However, I have come across one output  which I could not get the program
> to spit out. This is in regard to multiple mediators. I used the mediations
> and did my analysis for multiple mediators. Using the plot I get the simple
> graphs  (the ACME, direct effect and total effect) but could not perform
> the sensitivity analysis. Things that I tried and observed,
> >
> > X<-mediations(....)
> > names(X)
> > dliter.SR4.CSB (first mediator)
> > X1<-X$dliter.SR4.CSB
> > Then to do the sensitivity analysis
> > X1sens<-medsens(X1,rho.by=0.05)
> > Get an Error statement
> > I looked at the names of X1 and this is exactly same as the names if I
> did with one mediator.
> >
> > However. The problem is in the extract of model.y and model.m.
> > X1$model.y
> > NULL
> > X1$model.m
> > NULL
> >
> > These outputs are not available because the Mediations uses a glm method
> and it does not give me the output which is similar to the one that was
> produced using the lm procedure.  If you can please help me get the
> sensitivity analysis plots with multiple mediators, this is highly
> appreciated and acknowledged appropriately in my research. I even looked at
> plot.mediations but this gives the same plot as plot(X) two graphs of the
> ACME, direct effect and total effect. This is not what I am after but
> actually the sensitivity plots.
> >
> > Thanks for all your help and time.
> >
> > Kind regards.
> > I hope I made my point clear for you to provide your valuable guidance.
> > Murthy.N Mittinty.
> >
>
>
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