re: Re: st: Analyzing multiple mediators

["Ariel Linden, DrPH" <ariel.linden@gmail.com>]

I agree with Steve that sensitivity is important to apply to mediation
analysis. The only problem with -medeff- (the user written program that
Steve notes below that comes in a bigger package called -mediation-) is that
it does not handle multiple mediators. The R version of the program can
handle multiple mediators and perform sensitivity analysis, so if you want
to go this route, I suggest you read the paper by Kosuke Imai and Teppei
Yamamoto:

http://imai.princeton.edu/research/files/medsens.pdf

-khb- , which I noted earlier (findit khb), handles multiple mediators but
does not perform sensitivity analysis.

Ariel


Date: Sun, 25 Nov 2012 10:28:05 -0600
From: Steve Samuels <sjsamuels@gmail.com>
Subject: Re: st: Analyzing multiple mediators

Kim:

To answer your original question:  The error arose because you applied
the -if- expression only to -sureg- , not to the -bootmm- command.
- -jackknife-, called by the "bca" option, assumed that every observation
was in the estimation sample.

The fix:
  1. After the -syntax- statement in your program,
     add the statement:  "marksample touse".
  2. In place of "if NMV==1", substitute "if `touse'".
  3. In the -bootstrap- statement, after "bootmm", add "if NMV==1".

I agree with Ariel that -khb- offers a more comprehensive approach.
The -mediation- package by Hicks and Tingley (at SSC) is also worth
considering, because it does a sensitivity analysis of an important
assumption.


Reference:
Hicks, R., and D. Tingley. 2011. Causal mediation analysis. Stata
Journal 11, no. 4: 605. A preprint is as
http://scholar.harvard.edu/dtingley/software/mediation-stata.

(You can often find preprints with Google Scholar).


Steve


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