Tuesday, April 8, 2014


I've spent the last couple of days trying to replicate results in RATS that Chunbo produced using STATA. In the process we found a lot of bugs in our data-processing and computer codes but now we can replicate each others results. We are estimating a translog cost share system together with the cost function. Previously, I have used the RATS command SUR to estimate a system of seemingly unrelated regressions and then the command RESTRICT(replace) to impose the restrictions and SUR(CREATE) to produce the restricted SUR estimates. This did not reproduce the same results as STATA at all. Instead using NLSYSTEM in RATS (despite the fact that the system is linear), I managed to reproduce the same results as STATA. This now seems to be the recommended way to do this type of analysis according to the RATS User Guide. So, I really don't know what the estimates produced by RESTRICT in RATS represent and I strongly recommend not to use them. This shows yet again that it is very important to know what the computer code you are using is actually doing.

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