. 
. 
. ********** MEMORY MANAGEMENT
. set maxvar 100 width 1000
(maxvar and maxobs no longer need be set with this version of Stata)

. 
. 
. ********** READ DATA
. * See program stjaggia.asc for explanation of the following command
. * You need files jaggia.asc and jaggia.dct in your directory
. infile using jaggia.dct

dictionary using jaggia.asc {
 _column(1)   docno    %16.8f "Document Number"
 _column(17)  weeks    %17.8f "Weeks"
 _column(34)  numbids  %17.8f "Number of takeover bids (after the first)"
 _column(51)  takeover %17.8f "1 if takeover occurred, 0 otherwise"
 _newline 
 _column(1)   bidprem  %16.8f "Bid price / price 14 work days before bid"
 _column(17)  insthold %17.8f "Percentage of stock held by insitutions"
 _column(34)  size     %17.8f "Total book value of assets inb $billions " 
 _column(51)  leglrest %17.8f "Equals one if legal defense by lawsuit"
 _newline
 _column(1)   realrest %16.8f "One if proposed changes in asset structure"
 _column(17)  finrest  %17.8f "One if proposed changes in ownership struc"
 _column(34)  regulatn %17.8f "One if intervention by fed regulators"
 _column(57)  whtknght %17.8f "One if mgmt invite friendly 3rd-party bid"
* For this example the column numbers are redundant.
* Also the long labels need not be given.
}

(126 observations read)

. 
. 
. ********** DATA TRANSFORMATIONS
. gen sizesq = size*size

. label variable sizesq "size squared"

. 
. 
. ******** CHECK DATA: DESCRIPTIVE STATISTICS
. describe

Contains data
  obs:           126                          
 vars:            13                          
 size:         7,056 (99.2% of memory free)
-------------------------------------------------------------------------------
   1. docno     float  %9.0g                  Document Number
   2. weeks     float  %9.0g                  Weeks
   3. numbids   float  %9.0g                  Number of takeover bids (after
                                                the first)
   4. takeover  float  %9.0g                  1 if takeover occurred, 0
                                                otherwise
   5. bidprem   float  %9.0g                  Bid price / price 14 work days
                                                before bid
   6. insthold  float  %9.0g                  Percentage of stock held by
                                                insitutions
   7. size      float  %9.0g                  Total book value of assets inb
                                                $billions 
   8. leglrest  float  %9.0g                  Equals one if legal defense by
                                                lawsuit
   9. realrest  float  %9.0g                  One if proposed changes in
                                                asset structure
  10. finrest   float  %9.0g                  One if proposed changes in
                                                ownership struc
  11. regulatn  float  %9.0g                  One if intervention by fed
                                                regulators
  12. whtknght  float  %9.0g                  One if mgmt invite friendly
                                                3rd-party bid
  13. sizesq    float  %9.0g                  size squared
-------------------------------------------------------------------------------
Sorted by:  
     Note:  dataset has changed since last saved

. summarize

Variable |     Obs        Mean   Std. Dev.       Min        Max
---------+-----------------------------------------------------
   docno |     126    82174.41   2251.783      78001      85059  
   weeks |     126    11.44898   7.711424      2.857     41.429  
 numbids |     126    1.738095   1.432081          0         10  
takeover |     126           1          0          1          1  
 bidprem |     126    1.346806    .189325   .9426754   2.066366  
insthold |     126    .2518175   .1856136          0       .904  
    size |     126    1.219031   3.096624    .017722     22.169  
leglrest |     126    .4285714   .4968472          0          1  
realrest |     126    .1825397   .3878308          0          1  
 finrest |     126    .1031746   .3054011          0          1  
regulatn |     126    .2698413   .4456492          0          1  
whtknght |     126    .5952381   .4928054          0          1  
  sizesq |     126    10.99902   59.91479   .0003141   491.4646  

. 
. 
. ********** POISSON REGRESSION 
. *
. * Use /* and */ as command spans two lines
. 
. poisson numbids leglrest realrest finrest whtknght /* 
>     */ bidprem insthold size sizesq regulatn

Iteration 0:   log likelihood =  -184.9518  
Iteration 1:   log likelihood = -184.94833  
Iteration 2:   log likelihood = -184.94833  

Poisson regression                                Number of obs   =        126
                                                  LR chi2(9)      =      33.25
                                                  Prob > chi2     =     0.0001
Log likelihood = -184.94833                       Pseudo R2       =     0.0825

------------------------------------------------------------------------------
 numbids |      Coef.   Std. Err.       z     P>|z|       [95% Conf. Interval]
---------+--------------------------------------------------------------------
leglrest |   .2601464   .1509594      1.723   0.085      -.0357286    .5560213
realrest |  -.1956597   .1926309     -1.016   0.310      -.5732093    .1818899
 finrest |     .07403   .2165219      0.342   0.732      -.3503452    .4984053
whtknght |   .4813822   .1588698      3.030   0.002        .170003    .7927613
 bidprem |  -.6776959   .3767373     -1.799   0.072      -1.416087    .0606956
insthold |  -.3619913   .4243292     -0.853   0.394      -1.193661    .4696788
    size |   .1785026   .0600221      2.974   0.003       .0608614    .2961438
  sizesq |  -.0075693   .0031217     -2.425   0.015      -.0136878   -.0014509
regulatn |  -.0294392   .1605682     -0.183   0.855       -.344147    .2852686
   _cons |   .9860599   .5339202      1.847   0.065      -.0604044    2.032524
------------------------------------------------------------------------------

. 
. 
. ********** MAXIMUM LIKELIHOOD FOR POISSON
. 
. * Based on Weibull example in [R] ml - maximum likelihood
. * See especially Stata 6 Manual Reference H-O p.379 and p.388-399
. * The possible methods are lf, d0, d1 and d2. 
. * Here I use d0, d1 and d2 which give log-density etc for each observation.
. * I do not use lf which gives the log-likeihood over all observations
. 
. * The general form for the command is 
. * (1) Define the program, log-density, perhaps gradient and perhaps hessian  
>  
. *         program define myprog
. *            :  :
. *         end  
. * (2) Run the program providing dependent variable(s) and regressor(s)
. *       ml model d*** myprog (dep1 dep2 ... = x's for eqn1) (x's for eqn2) ..
>  
. *       ml maximize 
. *     where d*** called by d0, d1, d1debug, d2 and d2debug
. *     and the debug variants check anayltical against numerical derivatives
. *     and for robust standard errors based on A-in*B*A-inv add  , robust
. 
. 
. * For the Poisson log-density
. *       ln L = Sum_i {-mu_i + y_i*ln(mu_i) - ln(y_i!)}
. *   where
. *       mu_i = exp(x_i'b)
. *
. *   The first-order conditions are
. *       Sum_i (y_i - exp(x_i'b))x_i = 0
. *
. *   and the second-derivative matrix is
. *       Sum_i -exp(x_i'b))*x_i*x_i'              
.    
. 
. * (1) Define the program, log-density, perhaps gradient and perhaps hessian  
>  
. * The Poisson model is simple as only one index and one dependent variable
. * There is one dependent variable y which is stored in $ML_y1
. * There is one index which is x'b and for the Poisson model is mu i.e. E[y|x]
>  
. * For log-density  -mu_i + y_i*ln(mu_i) - ln(y_i!)   where mu_i = exp(x_i'b)
. * For gradient d/db = (y_i - mu_i)*x_i 
. * but Stata wands d/dtheta_i = (y_i - mu_i)  using theta_i = x_i'b  
. * For hessian      mu_i*x_i*x_i'
. * but Stata wants d2/dtheta_i^2 = mu_i  using theta_i = x_i'b  
. 
. * (2) Example is 
. * ml model d1debug mypois1 (numbids = bidprem) 
. * ml maximize
. 
. * For program debuggin which produces much output
. * set trace on
. 
. * The following programs are given
. *     mypois0  use numerical derivatives throughout
. *     mypois1  use analytical first derivative and numerical second
. *     mypois1r same as mypois1 but form robust variance matrix
. *     mypois2  use analytical first and second derivative
. *     mypois1  same as mypois1 but form robust variance matrix
. 
. 
. ******* (1) MYPOIS0 PROGRAM: POISSON WITH NUMERICAL DERIVATIVES THROUGHOUT
. 
. program define mypois0
  1.   version 6.0
  2.   args todo b lnf        /* Need to use the names todo b and lnf
>                             todo always contains 1 and may be ignored 
>                             b is parameters and lnf is log-density   */
  3.   tempvar theta1         /* create as needed to calculate lf, g, ... */
  4.   mleval `theta1' = `b', eq(1)   /* theta1 is theta1_i = x_i'b       */
  5.   local y "$ML_y1"       /* create to make program more readable     */ 
  6.   tempvar lnyfact mu
  7.   quietly gen double `lnyfact' = lnfact(`y')
  8.   quietly gen double `mu' = exp(`theta1')
  9.   mlsum `lnf' = -`mu' + `y'*ln(`mu') - `lnyfact'
 10. end

. 
. ******* (1) OUTPUT: POISSON WITH NUMERICAL DERIVATIVES THROUGHOUT
. 
. ml model d0 mypois0 (numbids = leglrest realrest finrest whtknght /* 
>     */ bidprem insthold size sizesq regulatn)

. ml maximize

initial:       log likelihood = -229.63257
alternative:   log likelihood = -201.87145
rescale:       log likelihood = -201.87145
Iteration 0:   log likelihood = -201.87145  
Iteration 1:   log likelihood =  -187.1169  
Iteration 2:   log likelihood = -184.95692  
Iteration 3:   log likelihood = -184.94833  
Iteration 4:   log likelihood = -184.94833  

                                                  Number of obs   =        126
                                                  Wald chi2(9)    =      33.79
Log likelihood = -184.94833                       Prob > chi2     =     0.0001

------------------------------------------------------------------------------
 numbids |      Coef.   Std. Err.       z     P>|z|       [95% Conf. Interval]
---------+--------------------------------------------------------------------
leglrest |   .2601464   .1509594      1.723   0.085      -.0357286    .5560214
realrest |  -.1956597    .192631     -1.016   0.310      -.5732096    .1818901
 finrest |     .07403    .216522      0.342   0.732      -.3503452    .4984052
whtknght |   .4813821   .1588698      3.030   0.002       .1700029    .7927613
 bidprem |  -.6776959   .3767378     -1.799   0.072      -1.416088    .0606967
insthold |  -.3619913   .4243294     -0.853   0.394      -1.193662    .4696792
    size |   .1785026   .0600224      2.974   0.003       .0608608    .2961444
  sizesq |  -.0075694   .0031217     -2.425   0.015      -.0136878   -.0014509
regulatn |  -.0294392   .1605682     -0.183   0.855      -.3441471    .2852686
   _cons |     .98606   .5339209      1.847   0.065      -.0604058    2.032526
------------------------------------------------------------------------------

. 
. 
. ******* (2) MYPOIS1 PROGRAM: POISSON WITH ANAYLTICAL FIRST DERIVATIVES
. 
. program define mypois1
  1.   version 6.0
  2.   args todo b lnf g      /* Need to use the names todo b and lnf
>                             todo always contains 1 and may be ignored 
>                             b is parameters, lnf is log-density
>                             g is gradient    */
  3.   tempvar theta1         /* create as needed to calculate lf, g, ... */
  4.   mleval `theta1' = `b', eq(1)   /* theta1 is theta1_i = x_i'b       */
  5.   local y "$ML_y1"       /* create to make program more readable     */ 
  6.   tempvar lnyfact mu
  7.   quietly gen double `lnyfact' = lnfact(`y')
  8.   quietly gen double `mu' = exp(`theta1')
  9.   mlsum `lnf' = -`mu' + `y'*ln(`mu') - `lnyfact'
 10.   /* Following code is extra for analytical first derivatives */
.   if `todo'==0 | `lnf'==. {exit}  
 11.   tempname d1
 12.   mlvecsum `lnf' `d1' = `y' - `mu'
 13.   matrix `g' = `d1'
 14. end

. 
. ******* (2) MYPOIS1 OUTPUT: POISSON WITH ANALYTICAL FIRST DERIVATIVES
. 
. ml model d1debug mypois1 (numbids = leglrest realrest finrest whtknght /* 
>         */ bidprem insthold size sizesq regulatn)

. ml maximize

initial:       log likelihood = -229.63257
alternative:   log likelihood = -201.87145
rescale:       log likelihood = -201.87145

d1debug:  Begin derivative-comparison report ---------------------------------
d1debug:  mreldif(gradient vector) =  .0011843
d1debug:  End derivative-comparison report -----------------------------------
Iteration 0:   log likelihood = -201.87145  

d1debug:  Begin derivative-comparison report ---------------------------------
d1debug:  mreldif(gradient vector) =  6.29e-09
d1debug:  End derivative-comparison report -----------------------------------
Iteration 1:   log likelihood =  -187.1169  

d1debug:  Begin derivative-comparison report ---------------------------------
d1debug:  mreldif(gradient vector) =  6.83e-07
d1debug:  End derivative-comparison report -----------------------------------
Iteration 2:   log likelihood = -184.95692  

d1debug:  Begin derivative-comparison report ---------------------------------
d1debug:  mreldif(gradient vector) =  .0003457
d1debug:  End derivative-comparison report -----------------------------------
Iteration 3:   log likelihood = -184.94833  

d1debug:  Begin derivative-comparison report ---------------------------------
d1debug:  mreldif(gradient vector) =  .0004541
d1debug:  End derivative-comparison report -----------------------------------
Iteration 4:   log likelihood = -184.94833  

                                                  Number of obs   =        126
                                                  Wald chi2(9)    =      33.79
Log likelihood = -184.94833                       Prob > chi2     =     0.0001

------------------------------------------------------------------------------
 numbids |      Coef.   Std. Err.       z     P>|z|       [95% Conf. Interval]
---------+--------------------------------------------------------------------
leglrest |   .2601464   .1509594      1.723   0.085      -.0357286    .5560214
realrest |  -.1956597    .192631     -1.016   0.310      -.5732096    .1818901
 finrest |     .07403    .216522      0.342   0.732      -.3503452    .4984052
whtknght |   .4813821   .1588698      3.030   0.002       .1700029    .7927613
 bidprem |  -.6776959   .3767378     -1.799   0.072      -1.416088    .0606967
insthold |  -.3619913   .4243294     -0.853   0.394      -1.193662    .4696792
    size |   .1785026   .0600224      2.974   0.003       .0608608    .2961444
  sizesq |  -.0075694   .0031217     -2.425   0.015      -.0136878   -.0014509
regulatn |  -.0294392   .1605682     -0.183   0.855      -.3441471    .2852686
   _cons |     .98606   .5339209      1.847   0.065      -.0604058    2.032526
------------------------------------------------------------------------------

. 
. 
. ******* (3) MYPOIS1r PROGRAM: ROBUST SE'S FOR POISSON ANAYLTICAL FIRST 
. 
. program define mypois1r
  1.   version 6.0
  2.   args todo b lnf g negH g1 /* Need to use the names todo b and lnf
>                             todo always contains 1 and may be ignored 
>                             b is parameters, lnf is log-density
>                             g is gradient negH need not be provided here
>                             g1 is to be used for robust se's         */
  3.   tempvar theta1         /* create as needed to calculate lf, g, ... */
  4.   mleval `theta1' = `b', eq(1)   /* theta1 is theta1_i = x_i'b       */
  5.   local y "$ML_y1"       /* create to make program more readable     */ 
  6.   tempvar lnyfact mu
  7.   quietly gen double `lnyfact' = lnfact(`y')
  8.   quietly gen double `mu' = exp(`theta1')
  9.   mlsum `lnf' = -`mu' + `y'*ln(`mu') - `lnyfact'
 10.   /* Following code is extra for analytical first derivatives 
>      and also changed due to robust se's   */
.   if `todo'==0 | `lnf'==. {exit}  
 11.   tempname d1
 12.   quietly replace `g1' = `y' - `mu' 
 13.   mlvecsum `lnf' `d1' = `g1'
 14.   matrix `g' = `d1'
 15. end

. 
. ******* (3) MYPOIS1r OUTPUT: ROBUST SE'S FOR POISSON ANAYLTICAL FIRST 
. 
. ml model d1debug mypois1r (numbids = leglrest realrest finrest whtknght /* 
>         */ bidprem insthold size sizesq regulatn), robust

. ml maximize

initial:       log likelihood = -229.63257
alternative:   log likelihood = -201.87145
rescale:       log likelihood = -201.87145

d1debug:  Begin derivative-comparison report ---------------------------------
d1debug:  mreldif(gradient vector) =  .0011843
d1debug:  End derivative-comparison report -----------------------------------
Iteration 0:   log likelihood = -201.87145  

d1debug:  Begin derivative-comparison report ---------------------------------
d1debug:  mreldif(gradient vector) =  6.29e-09
d1debug:  End derivative-comparison report -----------------------------------
Iteration 1:   log likelihood =  -187.1169  

d1debug:  Begin derivative-comparison report ---------------------------------
d1debug:  mreldif(gradient vector) =  6.83e-07
d1debug:  End derivative-comparison report -----------------------------------
Iteration 2:   log likelihood = -184.95692  

d1debug:  Begin derivative-comparison report ---------------------------------
d1debug:  mreldif(gradient vector) =  .0003457
d1debug:  End derivative-comparison report -----------------------------------
Iteration 3:   log likelihood = -184.94833  

d1debug:  Begin derivative-comparison report ---------------------------------
d1debug:  mreldif(gradient vector) =  .0004541
d1debug:  End derivative-comparison report -----------------------------------
Iteration 4:   log likelihood = -184.94833  

                                                  Number of obs   =        126
                                                  Wald chi2(9)    =      34.98
Log likelihood = -184.94833                       Prob > chi2     =     0.0001

------------------------------------------------------------------------------
         |               Robust
 numbids |      Coef.   Std. Err.       z     P>|z|       [95% Conf. Interval]
---------+--------------------------------------------------------------------
leglrest |   .2601464   .1250534      2.080   0.037       .0150462    .5052465
realrest |  -.1956597   .1816168     -1.077   0.281      -.5516222    .1603027
 finrest |     .07403   .2635711      0.281   0.779      -.4425598    .5906198
whtknght |   .4813821   .1064948      4.520   0.000       .2726562     .690108
 bidprem |  -.6776959    .297425     -2.279   0.023      -1.260638   -.0947536
insthold |  -.3619913   .3231802     -1.120   0.263      -.9954127    .2714302
    size |   .1785026    .062355      2.863   0.004        .056289    .3007161
  sizesq |  -.0075694   .0027788     -2.724   0.006      -.0130158   -.0021229
regulatn |  -.0294392   .1420508     -0.207   0.836      -.3078536    .2489752
   _cons |     .98606   .4137396      2.383   0.017       .1751453    1.796975
------------------------------------------------------------------------------

.   
. 
. ******* (4) MYPOIS2 PROGRAM: POISSON WITH ANAYLTICAL SECOND DERIVATIVES
. 
. program define mypois2
  1.   version 6.0
  2.   args todo b lnf g negH    /* Need to use the names todo b and lnf
>                             todo always contains 1 and may be ignored 
>                             b is parameters, lnf is log-density
>                             g is gradient, negH is negative hessian  */
  3.   tempvar theta1         /* create as needed to calculate lf, g, ... */
  4.   mleval `theta1' = `b', eq(1)   /* theta1 is theta1_i = x_i'b       */
  5.   local y "$ML_y1"       /* create to make program more readable     */ 
  6.   tempvar lnyfact mu
  7.   quietly gen double `lnyfact' = lnfact(`y')
  8.   quietly gen double `mu' = exp(`theta1')
  9.   mlsum `lnf' = -`mu' + `y'*ln(`mu') - `lnyfact'
 10.   /* Following code is extra for analytical first derivatives */
.   if `todo'==0 | `lnf'==. {exit}  
 11.   tempname d1
 12.   mlvecsum `lnf' `d1' = `y' - `mu'
 13.   matrix `g' = `d1'
 14.   /* Following code is extra for analytical second derivatives */ 
.   if `todo'==0 | `lnf'==. {exit}  
 15.   tempname d11
 16.   mlmatsum `lnf' `d11' = `mu'
 17.   matrix `negH' = `d11'
 18. end

. 
. ******* (4) MYPOIS2 OUTPUT: POISSON WITH ANALYTICAL SECOND DERIVATIVES
. 
. ml model d2debug mypois2 (numbids = leglrest realrest finrest whtknght /* 
>         */ bidprem insthold size sizesq regulatn)

. ml maximize

initial:       log likelihood = -229.63257
alternative:   log likelihood = -201.87145
rescale:       log likelihood = -201.87145

d2debug:  Begin derivative-comparison report ---------------------------------
d2debug:  mreldif(gradient vector) =  .0011843
d2debug:  mreldif(negative Hessian) =  .0006026
d2debug:  End derivative-comparison report -----------------------------------
Iteration 0:   log likelihood = -201.87145  

d2debug:  Begin derivative-comparison report ---------------------------------
d2debug:  mreldif(gradient vector) =  6.29e-09
d2debug:  mreldif(negative Hessian) =  .0419201
d2debug:  End derivative-comparison report -----------------------------------
Iteration 1:   log likelihood =  -187.1169  

d2debug:  Begin derivative-comparison report ---------------------------------
d2debug:  mreldif(gradient vector) =  6.83e-07
d2debug:  mreldif(negative Hessian) =  3.48e-06
d2debug:  End derivative-comparison report -----------------------------------
Iteration 2:   log likelihood = -184.95692  

d2debug:  Begin derivative-comparison report ---------------------------------
d2debug:  mreldif(gradient vector) =  .0003457
d2debug:  mreldif(negative Hessian) =  6.50e-07
d2debug:  End derivative-comparison report -----------------------------------
Iteration 3:   log likelihood = -184.94833  

d2debug:  Begin derivative-comparison report ---------------------------------
d2debug:  mreldif(gradient vector) =  .0004541
d2debug:  mreldif(negative Hessian) =  6.54e-07
d2debug:  End derivative-comparison report -----------------------------------
Iteration 4:   log likelihood = -184.94833  

                                                  Number of obs   =        126
                                                  Wald chi2(9)    =      33.79
Log likelihood = -184.94833                       Prob > chi2     =     0.0001

------------------------------------------------------------------------------
 numbids |      Coef.   Std. Err.       z     P>|z|       [95% Conf. Interval]
---------+--------------------------------------------------------------------
leglrest |   .2601464   .1509594      1.723   0.085      -.0357286    .5560214
realrest |  -.1956597    .192631     -1.016   0.310      -.5732096    .1818901
 finrest |     .07403    .216522      0.342   0.732      -.3503452    .4984052
whtknght |   .4813821   .1588698      3.030   0.002       .1700029    .7927613
 bidprem |  -.6776959   .3767378     -1.799   0.072      -1.416088    .0606967
insthold |  -.3619913   .4243294     -0.853   0.394      -1.193662    .4696792
    size |   .1785026   .0600224      2.974   0.003       .0608608    .2961444
  sizesq |  -.0075694   .0031217     -2.425   0.015      -.0136878   -.0014509
regulatn |  -.0294392   .1605682     -0.183   0.855      -.3441471    .2852686
   _cons |     .98606   .5339209      1.847   0.065      -.0604058    2.032526
------------------------------------------------------------------------------

. 
. 
. ******* (5) MYPOIS2r PROGRAM: ROBUST SE'S FOR POISSON ANAYLTICAL SECOND 
. 
. program define mypois2r
  1.   version 6.0
  2.   args todo b lnf g negH g1 /* Need to use the names todo b and lnf
>                             todo always contains 1 and may be ignored 
>                             b is parameters, lnf is log-density
>                             g is gradient negH need not be provided here
>                             g1 is to be used for robust se's         */
  3.   tempvar theta1         /* create as needed to calculate lf, g, ... */
  4.   mleval `theta1' = `b', eq(1)   /* theta1 is theta1_i = x_i'b       */
  5.   local y "$ML_y1"       /* create to make program more readable     */ 
  6.   tempvar lnyfact mu
  7.   quietly gen double `lnyfact' = lnfact(`y')
  8.   quietly gen double `mu' = exp(`theta1')
  9.   mlsum `lnf' = -`mu' + `y'*ln(`mu') - `lnyfact'
 10.   /* Following code is extra for analytical first derivatives 
>      and also changed due to robust se's   */
.   if `todo'==0 | `lnf'==. {exit}  
 11.   tempname d1
 12.   quietly replace `g1' = `y' - `mu' 
 13.   mlvecsum `lnf' `d1' = `g1'
 14.   matrix `g' = `d1'
 15.   /* Following code is extra for analytical second derivatives */ 
.   if `todo'==0 | `lnf'==. {exit}  
 16.   tempname d11
 17.   mlmatsum `lnf' `d11' = `mu'
 18.   matrix `negH' = `d11' 
 19. end

. 
. ******* (3) MYPOIS2r OUTPUT: ROBUST SE'S FOR POISSON ANAYLTICAL SECOND
. 
. ml model d2debug mypois2r (numbids = leglrest realrest finrest whtknght /* 
>         */ bidprem insthold size sizesq regulatn), robust

. ml maximize

initial:       log likelihood = -229.63257
alternative:   log likelihood = -201.87145
rescale:       log likelihood = -201.87145

d2debug:  Begin derivative-comparison report ---------------------------------
d2debug:  mreldif(gradient vector) =  .0011843
d2debug:  mreldif(negative Hessian) =  .0006026
d2debug:  End derivative-comparison report -----------------------------------
Iteration 0:   log likelihood = -201.87145  

d2debug:  Begin derivative-comparison report ---------------------------------
d2debug:  mreldif(gradient vector) =  6.29e-09
d2debug:  mreldif(negative Hessian) =  .0419201
d2debug:  End derivative-comparison report -----------------------------------
Iteration 1:   log likelihood =  -187.1169  

d2debug:  Begin derivative-comparison report ---------------------------------
d2debug:  mreldif(gradient vector) =  6.83e-07
d2debug:  mreldif(negative Hessian) =  3.48e-06
d2debug:  End derivative-comparison report -----------------------------------
Iteration 2:   log likelihood = -184.95692  

d2debug:  Begin derivative-comparison report ---------------------------------
d2debug:  mreldif(gradient vector) =  .0003457
d2debug:  mreldif(negative Hessian) =  6.50e-07
d2debug:  End derivative-comparison report -----------------------------------
Iteration 3:   log likelihood = -184.94833  

d2debug:  Begin derivative-comparison report ---------------------------------
d2debug:  mreldif(gradient vector) =  .0004541
d2debug:  mreldif(negative Hessian) =  6.54e-07
d2debug:  End derivative-comparison report -----------------------------------
Iteration 4:   log likelihood = -184.94833  

                                                  Number of obs   =        126
                                                  Wald chi2(9)    =      34.98
Log likelihood = -184.94833                       Prob > chi2     =     0.0001

------------------------------------------------------------------------------
         |               Robust
 numbids |      Coef.   Std. Err.       z     P>|z|       [95% Conf. Interval]
---------+--------------------------------------------------------------------
leglrest |   .2601464   .1250534      2.080   0.037       .0150462    .5052465
realrest |  -.1956597   .1816168     -1.077   0.281      -.5516222    .1603027
 finrest |     .07403   .2635711      0.281   0.779      -.4425598    .5906198
whtknght |   .4813821   .1064948      4.520   0.000       .2726562     .690108
 bidprem |  -.6776959    .297425     -2.279   0.023      -1.260638   -.0947536
insthold |  -.3619913   .3231802     -1.120   0.263      -.9954127    .2714302
    size |   .1785026    .062355      2.863   0.004        .056289    .3007161
  sizesq |  -.0075694   .0027788     -2.724   0.006      -.0130158   -.0021229
regulatn |  -.0294392   .1420508     -0.207   0.836      -.3078536    .2489752
   _cons |     .98606   .4137396      2.383   0.017       .1751453    1.796975
------------------------------------------------------------------------------

.   
. 
. ******* EXTRAS
. 
. * For models with two indexes see Weibull code in Stata 6 manual
. 
. 
. ********** CLOSE OUTPUT
. log close