Re: st: anchoring vignettes and gllamm problem

[Steve Samuels <sjsamuels@gmail.com>]

To be clearer, For non-linear models, you need at least 10 observations per predictor/
parameter.  See: www.psychosomaticmedicine.org/content/66/3/411.full.pdf.
So, you have enough for one predictor. So it's not surprising that you cannot
fit your model.

Steve

I'd say the problem is small sample size; there is information insufficient
information for finding a solution. 

Steve


On Jul 26, 2013, at 1:14 PM, Schuyler Blasy wrote:

Hello everyone,

I am having troubles with using -gllamm- command in applying it to
anchoring techniques; my Stata 12 will just continue to process and
not complete the computations. I am running on a windows 7 machine

Here is a bit of background. I am a just a masters student doing an
internship for a nonprofit that wants self-assessment surveys. I am
trying to incorporate the anchoring vignette technique into the
evaluation, but I am not too familiar with the Stata code and data
analysis part of it.

I found the Gary King article, and his simulated response/data with do
file and I was able to run it successfully on my computer.
http://www.gllamm.org/examples.html

However, when I tried to create my own data set and do file, Stata
gets hung up on the gllamm part and just never finishes computing.
Professor King’s data set and do file finish in about 4 to 5 minutes,
but mine has gone on for 10 hours with no end in sight.

There are differences in Professor King’s and mine data. Mine uses 3
vignettes with a scale of 0 through 10, and one self-assessment.  But,
I believe Professor King uses 5 vignettes with a scale of 1 through 5.

Also, I only tried my data set with 16 total observations, whereas
Professor King’s data set contained hundreds.

The part that Stata gets hung up on is:

gllamm xsay s_Treatment s_age s_male s_educyrs i1
> i2 i3, i(id) link(soprobit) s(het) ethresh(thresh)
> constr(1) init;

Can anyone give advice or an idea why my data set is not completing processing?

I sincerely appreciate any advice or input anyone has on this problem.
I have to admit, I am a Stata novice at best but I am learning, and I
am just a masters student, but I’m trying to do my best.

Appreciatively yours,

Schuyler Blasy

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