[Limdep Nlogit List] RE: Double Bounded (Probit)

[Sabah Abdullah]

Dear LIMDEP users:

I am running a maximum likelihood estimate (MLE) using a double
bounded dichtomous choice (DB DC) format where there are four
combinations of choices (YY, NN, YN, NY). I ran the following commands
(see below) and a return error message (see below). What does these
ERROR messages mean?

-Thank you for your time and consideration.

Regards, Ms. Abdullah

sample; all$
--> Maximize; labels=alpha,beta; start=0.25,0.25;
    fcn=YY*log(1-lgp(alpha+beta*BID_HIGH))
    +YN*log(lgp(alpha+beta*BID_HIGH)-lgp(alpha+beta*BID_INTL))
    +NY*log(lgp(alpha+beta*BID_INTL)-lgp(alpha+beta*BID_LOW))
    +NN*log(lgp(alpha+beta*BID_LOW))$
Error:   590: Obs.=     1 Cannot compute function: Logminus
Error:   137: Iterations: function not computable at crnt. trial estimate
Error:   802: Cannot compute function at start values. Exit status=4.
Function=  .00000000000D+00, at entry,  .00000000000D+00 at exit
Error:   590: Obs.=     1 Cannot compute function: Logminus
Error:   137: Iterations: function not computable at crnt. trial estimate
Error:   143: Models - estimated variance matrix of estimates is singular
Error:   447: Current estimated covariance matrix for slopes is singular.
--> wald; labels=alpha,beta; start=b(1),b(2); var=varb; fn1=-alpha/beta$
Error:    67: Matrix element in an expression has an invalid subscript.
Error:    32: Model command.  Start vals. unreadable or wrong # given.
Error:   208: MINIMIZE;...$  Start values not given or contain bad values


***********************************************
Sabah Abdullah
PhD Student (Economics)/Part-time Tutor/Resident Tutor
Dept. of Economics & Int'l Development
BATH
BA2 7AY
UNITED KINGDOM
e-mail:	s.abdullah at bath.ac.uk
WWW:	http://www.bath.ac.uk/~sa245