st: bootstrapping

[hsk22@cam.ac.uk]

Dear STATA users,

I would like to get estimates of coefficients and variances via 
bootstrapping. I used the travel choice data (from Econometric analysis 
from W. Greene). I run nested logit model and get results. After that, I 
run bootstrapping procedure by below command.

bs "nlogit choice (travel = aasc tasc basc cost ttime)(type=hincair), 
group(id)" "_b[ttime] _b[cost]", reps(100)

And then, I get the results as follows:

command:     nlogit choice (travel = aasc tasc basc cost ttime) 
(type=hincair),
group(id)
statistics:  _b[ttime] _b[cost]
(obs=840)

Bootstrap statistics

Variable |   Reps   Observed       Bias   Std. Err.   [95% Conf. Interval]
---------+-----------------------------------------------------------------
--
    bs1 |      0  -.1126183          .          .           .         . (N)
        |                                                   .         . (P)
        |                                                   .         . 
(BC)
---------+-----------------------------------------------------------------
--
    bs2 |      0  -.0315888          .          .           .         . (N)
        |                                                   .         . (P)
        |                                                   .         . 
(BC)
---------------------------------------------------------------------------
--
                             N = normal, P = percentile, BC = 
bias-corrected


I think there is some error. I would like to know how to deal with 
bootstrapping in nested logit model. Please let me know. Thanks in advance.

Best wishes,

Hanseung Kum


*
*   For searches and help try:
*   http://www.stata.com/support/faqs/res/findit.html
*   http://www.stata.com/support/statalist/faq
*   http://www.ats.ucla.edu/stat/stata/