[Limdep Nlogit List] WTP- space model: Confidence interval of WTP distribution using Delta method

Thao Thai Thao.T.Thai at monash.edu
Mon Apr 26 15:20:54 AEST 2021


Dear Nlogit users,

Please help if you can! Your help is much appreciated!

I ran a WTP-space model of which the results are below. Please help me
clarify some of my confusions:

(1) Is the confidence interval of the random parameters reported in the
model output, for example of the HOS variable, the confidence interval of
the mean WTP estimate for HOS variable?

(2) Does that mean the WTP distribution for HOS variable depends on the *mean
*WTP and its *standard error *(i.e. confidence interval of the mean WTP)
and the *standard deviation* (i.e. the estimated coefficients and standard
error for NsHOS) of the distribution for the WTP of HOS variables?

Please help:

(3) How can I compute the confidence intervals of WTPs distribution using
Delta method?
(4) How can I compute the confidence interval of the mean WTP using Delta
method? Is it the confidence interval reported in the WTP-space model
output?

Suppose the Delta method Wald syntax is

*Wald; Parameters = b; Covariance = varb*



*;Labels =  hos, pri, ind, gov, non, rlh1, rlh2, fl, cr1, cr2, lo1, sa,
rlc1, rlc2, lo2, rlp1, rli1, rli2, rlg1, rln1;Fn1 = ? ;Fn2 = ?*
*$*
I got confused about what to put in the function to get confidence
intervals of WTPs where the coefficients are already WTPs values?

I really look forward to your answers! Thank you in advance!
Best regards,
Thao
-----------------------------------------------------------------------------
Generalized Mixed (RP) Logit Model
Dependent variable                  CHO
Log likelihood function     -6513.18857
Restricted log likelihood  -12150.65191
Chi squared [ 39](P= .000)  11274.92669
Significance level               .00000
McFadden Pseudo R-squared      .4639639
Estimation based on N =   5530, K =  39
Inf.Cr.AIC  =  13104.4 AIC/N =    2.370
---------------------------------------
            Log likelihood R-sqrd R2Adj
No coefficients **********  .4640 .4628
Constants only can be computed directly
               Use NLOGIT ;...;RHS=ONE$
At start values -7718.0848  .1561 .1543
Note: R-sqrd = 1 - logL/Logl(constants)
Warning:  Model does not contain a full
set of ASCs. R-sqrd is problematic. Use
model setup with ;RHS=one to get LogL0.
---------------------------------------
Response data are given as ind. choices
Replications for simulated probs. =  50
Used Halton sequences in simulations.
RPL model with panel has     790 groups
Fixed number of obsrvs./group=        7
BHHH estimator used for asymp. variance
Number of obs.=  5530, skipped    0 obs
--------+--------------------------------------------------------------------
        |                  Standard            Prob.      95% Confidence
     CHO|  Coefficient       Error       z    |z|>Z*         Interval
--------+--------------------------------------------------------------------
        |Random parameters in utility
functions..............................
     HOS|    5.92660        8.03544      .74  .4608    -9.82257  21.67578
     PRI|    30.0879***     6.82100     4.41  .0000     16.7190   43.4568
     IND|   -74.2164***     8.56240    -8.67  .0000    -90.9984  -57.4344
     GOV|   -1.41410        7.62304     -.19  .8528   -16.35499  13.52679
     NON|    -.55721        7.71549     -.07  .9424   -15.67928  14.56486
    RLH1|   -4.88831        9.96395     -.49  .6237   -24.41730  14.64068
    RLH2|    15.4004**      7.46852     2.06  .0392       .7624   30.0385
      FL|    15.1360***     3.00154     5.04  .0000      9.2531   21.0189
     CR1|    33.4554***     3.29616    10.15  .0000     26.9950   39.9158
     CR2|    17.2478***     4.98946     3.46  .0005      7.4687   27.0270
     LO1|   -56.0650***     3.79442   -14.78  .0000    -63.5019  -48.6280
      SA|        1.0    .....(Fixed Parameter).....
    RLC1|    11.6994        9.01142     1.30  .1942     -5.9627   29.3614
    RLC2|    21.9054**      8.76364     2.50  .0124      4.7290   39.0818
     LO2|   -76.1803***     5.08817   -14.97  .0000    -86.1529  -66.2077
    RLP1|   -21.7674***     6.31574    -3.45  .0006    -34.1460   -9.3887
    RLI1|    36.7621***     9.08386     4.05  .0001     18.9581   54.5662
    RLI2|    48.4521***     6.98327     6.94  .0000     34.7651   62.1390
    RLG1|   -15.8780**      6.61678    -2.40  .0164    -28.8467   -2.9094
    RLN1|   -32.0373***     8.21917    -3.90  .0001    -48.1465  -15.9280
        |Distns. of RPs. Std.Devs or limits of
triangular....................
   NsHOS|    61.2749***     5.69437    10.76  .0000     50.1141   72.4356
   NsPRI|    52.0645***     5.48074     9.50  .0000     41.3224   62.8065
   NsIND|    81.7682***     6.32951    12.92  .0000     69.3626   94.1738
   NsGOV|    70.6895***     5.40187    13.09  .0000     60.1021   81.2770
   NsNON|    58.2880***     6.73963     8.65  .0000     45.0786   71.4975
  NsRLH1|    38.4853**     16.01183     2.40  .0162      7.1027   69.8679
  NsRLH2|    15.0987       14.26854     1.06  .2900    -12.8671   43.0645
    NsFL|    27.3007***     5.52125     4.94  .0000     16.4792   38.1221
   NsCR1|    1.25925        7.01920      .18  .8576   -12.49812  15.01662
   NsCR2|    9.06253        9.13084      .99  .3209    -8.83358  26.95864
   NsLO1|    58.1808***     4.70198    12.37  .0000     48.9651   67.3965
    CsSA|        0.0    .....(Fixed Parameter).....
  NsRLC1|    61.6887***     9.56351     6.45  .0000     42.9445   80.4328
  NsRLC2|    8.02381       13.69708      .59  .5580   -18.82197  34.86959
   NsLO2|    33.7236***     7.81182     4.32  .0000     18.4128   49.0345
  NsRLP1|    3.64345       12.20383      .30  .7653   -20.27562  27.56251
  NsRLI1|    52.0114***    13.12794     3.96  .0001     26.2811   77.7417
  NsRLI2|    7.20127       13.87235      .52  .6037   -19.98804  34.39057
  NsRLG1|    14.7726       11.03772     1.34  .1808     -6.8609   36.4061
  NsRLN1|    51.6333***     9.86131     5.24  .0000     32.3055   70.9611
        |Variance parameter tau in GMX scale
parameter.......................
TauScale|        0.0    .....(Fixed Parameter).....
        |Weighting parameter gamma in GMX
model..............................
GammaMXL|        0.0    .....(Fixed Parameter).....
        |Coefficient on SA       in preference space
form....................
Beta0WTP|     .01539***      .00043    35.64  .0000      .01454    .01623
S_b0_WTP|        0.0    .....(Fixed Parameter).....
        |  Sample Mean    Sample
Std.Dev.....................................
Sigma(i)|        1.0***   .1322D-05 ********  .0000  .10000D+01  .10000D+01
--------+--------------------------------------------------------------------
nnnnn.D-xx or D+xx => multiply by 10 to -xx or +xx.
***, **, * ==>  Significance at 1%, 5%, 10% level.
Fixed parameter ... is constrained to equal the value or
had a nonpositive st.error because of an earlier problem.
Model was estimated on Apr 23, 2021 at 08:10:02 PM
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