1-1-1 multi-level mediation with a mo... PreviousNext
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 Tsachi Ein-Dor posted on Thursday, February 10, 2011 - 1:44 am
I have a 1-1-1 mediation (see below an MSEM code). My problem is that I have a level 2 moderator as well. As far as I could understand, level 2 measures can influence level 2 constructs (between), but not level 1 (within). Am I right so far? If so can someone help with the implementation of that into the code below?

TITLE: 1-1-1 mediation (MSEM)
DATA: FILE IS mydata.dat;
VARIABLE: NAMES ARE
id x m y;
USEVARIABLES ARE
id x m y;
CLUSTER IS id;
ANALYSIS: TYPE IS TWOLEVEL RANDOM;
MODEL:
%WITHIN%
m ON x(aw); ! regress m on x, call the slope "aw"
y ON m(bw); ! regress y on m, call the slope "bw"
y ON x; ! regress y on x
%BETWEEN%
x m y; ! estimate Level-2 (residual) variances for x, m, and y
m ON x(ab); ! regress m on x, call the slope "ab"
y ON m(bb); ! regress y on m, call the slope "bb"
y ON x; ! regress y on x
MODEL CONSTRAINT: ! section for computing indirect effects
NEW(indb indw); ! name the indirect effects
indw=aw*bw; ! compute the Within indirect effect
indb=ab*bb; ! compute the Between indirect effect
OUTPUT: TECH1 TECH8 CINTERVAL; ! request parameter specifications, starting values,
! optimation history, and confidence intervals for all effects

Sincerely,
 Bengt O. Muthen posted on Thursday, February 10, 2011 - 11:20 am
I am not into the numbering approach of characterizing two-level mediation modeling, but looking at Bauer et al (2006) in Psych Methods Figure 2, bottom, it looks to me that 1-1-1 mediation has a mediation model on the Within level and unrestricted random effects on the Between level. You pose a model for the random effects on Between. It happens to be a saturated model so it becomes the same as unrestricted.

Then you say "level 2 measures can influence level 2 constructs (between), but not level 1 (within)." Let's scrutinize the second part of that statement. It sounds like you want "2-2-1" as in top of Figure 2. Using an education example, you have a teacher background variable influencing a teacher dependent variable (2-2) which you want to influence a student dependent variable (2-2-1). This is done by letting the teacher dependent variable influence the between-level part of the student variable on Between, that is the random intercept (varying over teachers/classrooms) of the student variable. The model you have written in your Mplus input does this with both M and Y having between-level random intercepts.

I don't see any moderator in your Mplus input. A moderator is an interaction.
 Bengt O. Muthen posted on Thursday, February 10, 2011 - 11:51 am
You may also want to take a look at the Topic 7 handout on our web site. Slides 44-45 talk about random intercepts and random slopes (cross-level interaction).
 Sean Lane posted on Wednesday, August 24, 2011 - 9:47 am
I'm trying to fit a model similar to that listed above (using the Bauer et al syntax), but I get an error message saying that Monte Carlo integration is needed. When I specify Monte Carlo integration I get another error message saying that within-person variables cannot be on the right hand side of an ON statement. However, since I didn't specify any variables as BETWEEN I should be able to use them as WITHIN or BETWEEN, right?

VARIABLE: NAMES ARE
myid pol anger attackm;
MISSING ARE ALL (-99);
USEVARIABLES ARE myid pol anger attackm;
CLUSTER IS myid;
ANALYSIS: TYPE IS TWOLEVEL RANDOM;
!ALGORITHM = INTEGRATION;
!INTEGRATION = MONTECARLO;
MODEL:
%WITHIN%
sa | anger ON pol;
sb | attackm ON anger;
sc | attackm ON pol;
%BETWEEN%
sa sb sc pol anger attackm;
sa WITH sc pol anger attackm;
sa WITH sb(cab);
sb WITH sc pol anger attackm;
sc WITH pol anger attackm;
anger ON pol(ab);
attackm ON anger(bb);
attackm ON pol;
[sa](aw); [sb](bw);
MODEL CONSTRAINT:
NEW(a b indb indw);
a=aw+ab; ! compute Between a path
b=bw+bb; ! compute Between b path
indw=aw*bw+cab; ! compute the Within indirect effect
indb=a*b; ! compute the Between indirect effect
OUTPUT: TECH1 TECH8 CINTERVAL;

Any help is greatly appreciated. Thanks!
 Linda K. Muthen posted on Wednesday, August 24, 2011 - 1:05 pm
Please send the full output and your license number to support@statmodel.com.
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