**************************************************************
* cfkids-lmm-gee.do                                          *
**************************************************************
*                                                            *  
* PURPOSE:  regression analysis of FEV1 among CF kids        *
*                                                            *
* AUTHOR:  P. Heagerty                                       *
*                                                            *
* DATE:  05 April 2005                                       *
*        04 April 2006                                       *  
**************************************************************

use NewCFkids

***
*** create the interactions and dummy variables
***

gen f508_1 = (f508==1)
gen f508_2 = (f508==2)

gen ageXf508_1 = f508_1 * ageL
gen ageXf508_2 = f508_2 * ageL

gen ageXgender = gender * ageL

*****
***** Linear Mixed Model Analysis
*****


******************************************************
***  analysis using GLLAMM  (old; slow; general)            ***
******************************************************
  
gen cons=1

eq int: cons
eq slope: ageL

set more off

*** Model 1:  Random Intercepts

*gllamm fev1 age0 ageL gender f508_1 f508_2 ageXgender ageXf508_1 ageXf508_2,           i(id) eqs(int) nrf(1) nip(10) adapt

*** Model 2:  Random Intercepts and Slopes

*gllamm fev1 age0 ageL gender f508_1 f508_2 ageXgender ageXf508_1 ageXf508_2,           i(id) eqs(int slope) nrf(2) nip(10) adapt

******************************************************
***  analysis using XTMIXED                        ***
******************************************************

*** Model 1:  Random Intercepts

xtmixed fev1 age0 ageL gender f508_1 f508_2 ///
             ageXgender ageXf508_1 ageXf508_2     ||  id: 

*** Model 2:  Random Intercepts and Slopes

xtmixed fev1 age0 ageL gender f508_1 f508_2 ///
             ageXgender ageXf508_1 ageXf508_2     || id: ageL, cov(un)


  
*****
***** Generalized Estimating Equations Analysis
*****  

* standard (independent data) regression *
regress fev1 age0 ageL gender f508_1 f508_2 ageXgender ageXf508_1 ageXf508_2


xtgee fev1 age0 ageL gender f508_1 f508_2 ageXgender ageXf508_1 ageXf508_2,            corr(independent) i(id) nmp

xtcorr

xtgee fev1 age0 ageL gender f508_1 f508_2 ageXgender ageXf508_1 ageXf508_2,            corr(independent) i(id) robust


xtgee fev1 age0 ageL gender f508_1 f508_2 ageXgender ageXf508_1 ageXf508_2,            corr(exchangeable) i(id)

xtcorr

xtgee fev1 age0 ageL gender f508_1 f508_2 ageXgender ageXf508_1 ageXf508_2,           corr(exchangeable) i(id) robust