st: RE: how to plot growth curves from two separate multilevel models in one graph

["W.O.Johnson" <W.O.Johnson@lboro.ac.uk>]

Hi Nick, 

I want to fit two MLM growth models (weight age log_age inverse_age plus covariates) using the xtmixed command in stata to two different samples. Fitting the models is no problem, but I can not find a way to plot the mean constant growth curves for each sample in one graph. The command I am using to produce a growth curve is 'twoway (function weight = _b[_cons] + _b[age]*(x) + _b[log_age]*ln(x) +_b[inverse_age]*1/(x)'. The problem is that as soon as I fit the second model the parameter estimates are changed?? 

Will 




-------------------------------------------

Dr William Johnson

Research Associate
Centre for Global Health and Human Development
School of Sport, Exercise and Health Sciences 
Loughborough University
Leicestershire
LE11 3TU
United Kingdom

t: +44 (0) 1509 228159
e: W.O.Johnson@lboro.ac.uk 
-----Original Message-----
From: owner-statalist@hsphsun2.harvard.edu [mailto:owner-statalist@hsphsun2.harvard.edu] On Behalf Of Nick Cox
Sent: 02 August 2010 18:05
To: statalist@hsphsun2.harvard.edu
Subject: st: RE: how to plot growth curves from two separate multilevel models in one graph

I imagine that Stata could do this. Given some exact detail on what you
want to plot, I imagine that a better answer is also possible. 

Nick 
n.j.cox@durham.ac.uk 

W.O.Johnson

I am running an analysis that requires me to fit multilevel growth
models to two different samples (I need to use one model for use
sample). I want to plot the resulting growth curves for each sample in
one graph, but do not know if Stata can do this. Any advice will be
gratefully received. 


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