Gauss code for Eklof, J and S Karlsson, "Testing and Correcting for Sample
Selection Bias in Discrete Choice Contingent Valuation Studies".

The sim*.g files run the simulations for the specified value of rho
(the correlation between the equations) for each of the cases discussed in
the paper. Case 3a corresponds to Case 3 with delta = -0.5 in the paper and
3b corresponds to delta = 0.5. Each simulation run saves the results to a
large (about 2.5 MB) *.fmt file and the res*.g file calculates the summary
statistics given in the paper.

The zip-file d_choice.zip contains a Gauss-library implementing the the tests
and estimators used in the paper. A few additional limited observability
estimators are also implemented as well as univariate logit and probit.
Put the *.lcg file in your GAUSS\LIB directory and the remaining files in
the GAUSS\SRC directory.

Sune Karlsson, stsk@hhs.se