[Limdep Nlogit List] Nlogit Error 352: Model with Panel. Sum of T(i) not equal to full sample size

[Akram Ahmad]

Hi everybody,

I have a question regarding Mixed logit model. For my research I want to investigate patients' preferences for conventional or Ayurvedic medicines for the treatment of diabetes and investigate what factors could affect patients' preferences.

In a labelled d-efficient design, which will have 3 alternatives where the last alternative would be a no-choice alternative. There were 8 attributes (7 of them have 3 levels and 1 attribute has 2 levels). We will be giving 8 choice tasks to each participant and block the design into 4 versions (for 32 tasks). Negative signs in the values indicate that the particular attribute will negatively contribute to the utilisation of the given alternative. For example, side-effects will decrease the utility of the medication (both conventional and alternative).
Here is my syntax for your perusal. The syntax error is popping up [Error    352: Model with Panel. Sum of T(i) not equal to full sample size]
Any help would be appreciated.

Mixed logit model

NLOGIT
;lhs=choice,cset,altij
;choices=CM,AM,NEITHER
;rpl
;fcn=effec(n),sidef(n),dosage(n),formu(n),instruct(n),hypo(n),weight(n),cost(n)
;pts=500 ;halton
;pds=nchoice
;model:
U(cm)=cm+effec1*effec1+ effec2*effec2+ sidef1*sidef1+sidef2*sidef2+dosage1*dosage1+ dosage2*dosage2+formu1*formu1+formu2*formu2+instruct*instruct+hypo1*hypo1+hypo2*hypo2+weight1*weight1+weight2*weight2+cost1*cost1+cost2*cost2/
U(am)=am+effec1*effec1+ effec2*effec2+ sidef1*sidef1+sidef2*sidef2+dosage1*dosage1+ dosage2*dosage2+formu1*formu1+formu2*formu2+instruct*instruct+hypo1*hypo1+hypo2*hypo2+weight1*weight1+weight2*weight2+cost1*cost1+cost2*cost2/
U(neither)=0
$

Regards,
Akram Ahmad
PhD student at School of Pharmacy, the University of Sydney.