[Limdep Nlogit List] Help with LCM

Alec Miners Alec.Miners at lshtm.ac.uk
Wed Jan 20 01:03:50 AEDT 2016


Dear All

Apologies I meant when pts>2  NOT pds>2

I should also add I have no missing data. So it can't be this causing the problem. 

Bw Alec


                              From: Alec Miners
Sent: Tuesday, 19 January 2016 13:17
To: limdep at limdep.itls.usyd.edu.au
Subject: Help with LCM






Dear All

I am analysing a labelled DCE, using both dummy and effects coded models, using a LCM.  There are 5 alternatives, and each respondent completed 12 DCE questions

The two models give exactly the same log-l'hoods (ie the fit is the same), when i exclude any class parameters (eg. age) from the LCM line. ie using the syntax below. Clearly the coefficients are different.  Fine up to this point using the code below

NLOGIT
;checkdata
;choices = CHAT,ONLINEGR,ONLINE1T, EMAILORT, NONE
;lhs= choice1
;rhs = ONLINEGR,ONLINE1T, CHAT, NONE, EF2FGROU, EPHONE1T, ESESSION, ESESSIO0, EMINS15T,EMINS30T, ENURSE, EPEER
;LCM
;pds=12
;pts=3
$
  
NLOGIT
;checkdata
;choices = CHAT,ONLINEGR,ONLINE1T, EMAILORT, NONE
;lhs= choice1
;rhs = ONLINEGR,ONLINE1T, CHAT, NONE, DF2FGROU, DPHONE1T, DSESSION, DSESSIO0, DMINS15T,DMINS30T, DNURSE, DPEER
;LCM
;pds=12
;pts=3
$

However, when I start including statements such as (in both the effects and dummy models)

;LCM = d_young (a 0/1 variable indicating whether someone is young or not), the model fits and class proportions begin to differ but only when pds > 2. 

I am confused as to why this would be the case??


All help much appreciated

Bw Alec

Alec Miners, PhD
Senior Lecturer in Health Economics
Dept Health Services Research & Policy
London School of Hygiene and Tropical Medicine
Room 134
15-17 Tavistock Place 
London 
WC1H 9SY

Tel 0207 927 2069
Fax 0207 580 8183






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