st: re: standardized betas with nlcom

[Amy Hale <aehale38@gmail.com>]

Hi Statalisters,

I'm running some moderated mediation models and need to obtain
standardized betas, but when I added - estat stdize: - to the - nlcom-
command line the z and p-values changed dramatically (e.g. before
adding - estat stdize: - p value was .015, after it was .881).  Any
ideas what might be happening?

The code I'm using is:

sem (med1 <- indvar mod interact) (med2 <- indvar mod interact)
(depvar <- med1 med2 indvar mod interact), standardized

summarize mod
global m = r(mean)
global s = r(sd)

estat stdize: nlcom (_b[med1:indvar]+($m-$s)*_b[med1:wx])*_b[depvar:med1]
estat stdize: nlcom (_b[med1:indvar]+($m)*_b[med1:wx])*_b[depvar:med1]
estat stdize: nlcom (_b[med1:indvar]+($m+$s)*_b[med1:wx])*_b[depvar:med1]
estat stdize: nlcom (_b[med2:indvar]+($m-$s)*_b[med2:wx])*_b[depvar:med2]
estat stdize: nlcom (_b[med2:indvar]+($m)*_b[med2:wx])*_b[depvar:med2]
estat stdize: nlcom (_b[med2:indvar]+($m+$s)*_b[med2:wx])*_b[depvar:med2]
estat stdize: nlcom
(_b[med1:indvar]+($m-$s)*_b[med1:wx])*_b[depvar:med1]+
(_b[med2:indvar]+($m-$s)*_b[med2:wx])*_b[depvar:med2]
estat stdize: nlcom (_b[med1:indvar]+($m)*_b[med1:wx])*_b[depvar:med1]
+ (_b[med2:indvar]+($m)*_b[med2:wx])*_b[depvar:med2]
estat stdize: nlcom
(_b[med1:indvar]+($m+$s)*_b[med1:wx])*_b[depvar:med1] +
(_b[med2:indvar]+($m+$s)*_b[med2:wx])*_b[depvar:med2]


key:
*med1 = mediator #1
*med2 = mediator #2
*mod = moderator
*interact = interaction term
*indvar = independent variable
*depvar = dependent variable

Should I be using a different command to get standardized betas with
-nlcom-, or am I missing something obvious?

Thanks,
Amy
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