Use the Koppelman dataset. Estimate a general multinomial probit model similar to that reported in Table 26.1 but with the following modifications. For each case report the estimated coefficients and standard errors for the cost and time variables, the log-likelihood, and describe how the results change.

(a) Replicate the results of Table 26.1 for multinomial probit with the same variables.

(b) Replace cost and intime with log(cost) and log(intime).