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Re: st: GLLAMM: Predict Class Membership


From   m.spitzenpfeil@gmx.net
To   statalist@hsphsun2.harvard.edu
Subject   Re: st: GLLAMM: Predict Class Membership
Date   Wed, 19 Sep 2012 14:13:03 +0200

I've already assigned the individuals according to the conditional (conditional on the observed variables)
probabilities of belonging to the class (class 1 instead of 0).

Since there are only two classes i expected the mean of the class variable
to equal the prior probability of belonging to class 1.
That's not the case, though.

Thanks for the references!

Martin

Am 19.09.2012 14:05, schrieb Cameron McIntosh:
You will often see people assigning cases to classes based on posterior probabilities (usually to run separate logistic regressions of classes on covariates), but this removes uncertainty in class membership and thus biases standard errors of coefficients downward.  So optimally you would use a concomitant-variable LCA, or improved multi-step approaches:

Vermunt, J.K. (2010). Latent Class Modeling with Covariates: Two Improved Three-Step Approaches. Political Analysis, 18(4), 450-469.

Clark, S. & Muthén, B. (submitted). Relating latent class analysis results to variables not included in the analysis.
http://www.statmodel.com/download/relatinglca.pdf

Cam

Date: Wed, 19 Sep 2012 12:34:42 +0200
From: m.spitzenpfeil@gmx.net
To: statalist@hsphsun2.harvard.edu
Subject: st: GLLAMM: Predict Class Membership

Hi,

is there any way to predict individual latent class membership
as a dummy variable - and not in terms of probability - using
GLLAMM?

My modell is structurally equivalent to the Myocardial Infarction Example:
http://www.gllamm.org/examples.html
http://www.gllamm.org/data_dofile.zip

insheet using mi.dat, clear
rename q y1
rename h y2
rename l y3
rename c y4
gen wt2 = count
gen patt=_n

reshape long y, i(patt) j(var)
tab var, gen(v)

eq v1: v1
eq v2: v2
eq v3: v3
eq v4: v4

gllamm y, i(patt) ip(fn) nip(2) eqs(v1 v2 v3 v4) /*
*/ weight(wt) nrf(4) l(logit) f(binom) nocons



Thanks for your help!

Martin
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