Combining LOOP with DO PreviousNext
Mplus Discussion > Structural Equation Modeling >
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 S.Arunachalam posted on Monday, August 26, 2013 - 9:55 am
Respected Prof. Muthen,

I am trying to get significance for each value of x (moderator) in my moderated-mediation model using

MODEL CONSTRAINT:
new(ind1-ind21);
loop (x,-1,1,.1);
do (1,21) ind# = b1 * (a1 + a2 * x);

However the results report the same value for all the 21 indirect effect as
IND1 0.047 0.024 1.997 0.046
IND2 0.047 0.024 1.997 0.046
IND3 0.047 0.024 1.997 0.046
.... ........
IND21 0.047 0.024 1.997 0.046

While I can use PLOT(ind) to get the plot, I need the significance of the indirect effect for every legitimate value of X ( similar to Johnson-Neuman technique) which I am not getting using the PLOT(ind). My apologies if I am missing something very obvious, please guide.
 Bengt O. Muthen posted on Monday, August 26, 2013 - 2:31 pm
The DO function is not connected to LOOP. Instead follow page 16 of the May 2013 UConn Workshop handout on our website which shows how LOOP is connected with PLOT to do what you want:

MODEL CONSTRAINT:
PLOT(indirect direct);
! let moderate represent the range of the agg1 moderator
LOOP(moderate, -2, 2, 0.1);
indirect = beta1*(gamma1+gamma3*moderate);
direct = beta2+beta4*moderate;
 S.Arunachalam posted on Monday, August 26, 2013 - 4:28 pm
Dear Prof. Muthen, Yes I did use the PLOT to get the graph. However the PLOT doesn't print the values of the confidence limits (in the .out file) for the different values of the moderator. I need those to be reported in my article to show the points where the moderated-mediation is significant at 95% level. Is there a way to get those confidence limits which PLOT uses to be printed in the .out file? Thank you.
 Thuy Nguyen posted on Monday, August 26, 2013 - 4:56 pm
You can use the “Save plot data” option under the Plot menu to save the values plotted in the loop plot. The file will contain 4 columns of data. The first column has the x-values; the second column has the estimates; the third column has the lower confidence limit; and the fourth column has the upper confidence limit.
 S.Arunachalam posted on Monday, August 26, 2013 - 5:01 pm
Thank you so much, Thuy! I truly appreciate it.
Respectfully, Arun
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