Hello All, After running into some difficulties with missing data, we are looking into replicating one of our backup choices for papers. This paper employs a two-stage tobit model. We gather the model is similar to a two-stage least squares model in that one uses instrumental variables to deal with the situation when at least some independent variable (xi) is correlated with at least some stochastic component. We also understand the tobit model allows one to deal with censored data (e.g. non-negative y). We are wondering if anyone has experience running the tobit model in Zelig, or programming in R a two-stage model using this concept of instrumental variables. If so, perhaps we can ask you some specific questions that have arisen in our replication. The authors of our paper used Stata, which unfortunately for us, has a pre-programmed IV tobit function and provides little clue to what the function actually does (something of a 'black box'). Thank you in advance! Lauren (+ John Polley) _______________________________________________ gov2001-l mailing list gov2001-l at lists.fas.harvard.edu http://lists.fas.harvard.edu/mailman/listinfo/gov2001-l