[Limdep Nlogit List] Need a kind help

[William Greene]

Mr. Bilgic: I can't vouch for the code for the likelihood function.
But, you are using 0 and 0 for the starting values for the variances,
so it's for sure that you cannot compute the function at the starting
values. That is the source of the problems.
/B. Greene

************************************************
Professor William Greene
Department of Economics
Stern School of Business
New York University
44 West 4th St., Rm. 7-78
New York, NY   10012
Ph. 212.998.0876
Fax. 212.995.4218
URL. http://www.stern.nyu.edu/~wgreene
Email. wgreene at stern.nyu.edu
************************************************

----- Original Message -----
From: Abdulbaki Bilgic <tebrik at yahoo.com>
Date: Thursday, April 6, 2006 12:27 pm
Subject: [Limdep Nlogit List] Need a kind help

>  Dear Limdep Users,
>  I am estimating a bivariate tobit model with three switching 
> regimes: (y1>0, y2=0), (y1=0,y2>0), and (y1>0, y2>0). The last 
> term where both y1 and y2 greater than 0 is the conditional 
> distribution of y2 given y1 >0. I have written a code in Limdep 
> and got a error reporting a zero division and i have checked the 
> reference book it says a dependent variable problem and when 
> deleting the first observation, it gives the same problem too. Any 
> ideas please.
>   
>   
>  CREATE ; IF(Y1 = 0 & Y2 =0)DUMMY1=1
>  ; (ELSE) DUMMY1=0
>  ; IF(Y1 > 0 & Y2 =0)DUMMY2=1
>  ; (ELSE) DUMMY2=0
>  ; IF(Y1 = 0 & Y2 >0)DUMMY3=1
>  ; (ELSE) DUMMY3=0
>  ; IF(Y1 > 0 & Y2 >0)DUMMY4=1
>  ; (ELSE) DUMMY4=0 $
>  NAMELIST ; X1 =ONE
>  ; X2 =ONE $
>  CALC ; LIST
>  ; KA=COL(X1)
>  ; KB=COL(X2)
>  ; KC=KA+1 
>  ; KD=KA+KB $
>  MATRIX ; LIST
>  ; CA=INIT(KA,1,.0)
>  ; CB=INIT(KB,1,.0) $
>  MAXIMIZE ; START =CA,CB,.0,.0,.0
>  ; LABELS=KA_BA, KB_BB,SIGM1,SIGM2,RHO12
>  ; FCN=TA1 =LOG((1+RHO12)/(1-RHO12)) |
>  RHO12 =(EXP(TA1)-1)/(EXP(TA1)+1) |
>  SG1 =1/(SIGM1*(SQR(1-RHO12^2))) | 
>  SG2 =1/(SIGM2*(SQR(1-RHO12^2))) |
>  SG3 =1/(SIGM2^2*(SQR(1-RHO12^2))) |
>  ETA1 =1/(2*SIGM1^2) |
>  ETA2 =1/(2*SIGM2^2) |
>  ETRHO1 =RHO12*(SIGM1/SIGM2) |
>  ETRHO2 =RHO12*(SIGM2/SIGM1) |
>  RHOSQ =(1-RHO12^2) |
>  INDEX1 =BA1'X1 |
>  INDEX2 =BB1'X2 |
>  ERROR1 =Y1-INDEX1 |
>  ERROR2 =Y2-INDEX2 |
>  INDX1 =INDEX1+ETRHO1*ERROR2 |
>  INDX2 =INDEX2+ETRHO2*ERROR1 |
>  INDXX1 =-SG1*INDX1 |
>  INDXX2 =-SG2*INDX2 |
>  DUMMY2*(-0.5*LOG(2*PI)-LOG(SIGM1)-ETA1*ERROR1^2+LOG(PHI(INDXX2)))+
>  DUMMY3*(-0.5*LOG(2*PI)-LOG(SIGM2)-ETA2*ERROR2^2+LOG(PHI(INDXX1)))+
>  DUMMY4*(-0.5*LOG(2*PI)-LOG(SIGM1)-ETA1*ERROR1^2-2*LOG(SIGM2)
>  -0.5*LOG(RHOSQ)-SG3*(Y2-INDX2)^2) 
>  ; ALG=N 
>  ; TLF=1.D-8
>  ; TLG=1.D-4
>  ; SET $
>   
>  Output is:
>  Error 590: Obs.= 1 Cannot compute function: Zero_dvd
>  Warning 137: Iterations: function not computable at crnt. trial 
> estimate  Error 802: Cannot compute function at start values. Exit 
> status=4.  Function= .36023626764D+05, at entry, .00000000000D+00 
> at exit
>  +---------------------------------------------+
>  | User Defined Optimization |
>  | Maximum Likelihood Estimates |
>  | Model estimated: Apr 06, 1999 at 04:18:24PM.|
>  | Dependent variable Function |
>  | Weighting variable None |
>  | Number of observations 22344 |
>  | Iterations completed 0 |
>  | Log likelihood function .0000000 |
>  | Number of parameters 0 |
>  | Info. Criterion: AIC = .00000 |
>  | Finite Sample: AIC = .00000 |
>  | Info. Criterion: BIC = .00000 |
>  | Info. Criterion:HQIC = .00000 |
>  +---------------------------------------------+
>  +---------+--------------+----------------+--------+---------+
>  |Variable | Coefficient | Standard Error |b/St.Er.|P[|Z|>z] |
>  +---------+--------------+----------------+--------+---------+
>  BA1   .000000 1.00000000 .000 1.0000
>  BB1   .000000 1.00000000 .000 1.0000
>  SIGM1 .000000 1.00000000 .000 1.0000
>  SIGM2 .000000 1.00000000 .000 1.0000
>  RHO12 .000000 1.00000000 .000 1.0000
>    
>  Best regards,
> 
> 
> 
>                	
> ---------------------------------
> Yahoo! Messenger with Voice. PC-to-Phone calls for ridiculously 
> low rates.
> _______________________________________________
> Limdep site list
> Limdep at limdep.itls.usyd.edu.au
> http://limdep.itls.usyd.edu.au
>