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From | "Alvarez,Sergio" <sergioal@ufl.edu> |
To | <statalist@hsphsun2.harvard.edu> |
Subject | Re: st: nested logit tree |
Date | Mon, 28 Nov 2011 11:02:27 -0500 |
Solon,I may be misunderstanding, but it looks like you want to model a decision which has only two possible outcomes: firm is a supplier or firm is a buyer. If that is the case, you probably should use a probit or logit rather than a nested logit. You can also model whether the firm has an R&D department (yes or no) using a similar approach.
The nested and conditional logits are used when you have an agent (a firm) making a choice among many alternatives (more than two).
Take a look at the restaurant.dta sample dataset and the nlogit help file and it will become clear.
Best, Sergio On Mon, 28 Nov 2011 14:39:19 +0100, Solon Moreira wrote:
Dear Stata list readers, This is a question regarding the way that I should structure the tree of a nested logit model to get the right output. I have a dataset consisting of 1200 firms that buy and selltechnologies. I am trying to run a model in which in the first level I can observe how firm-specific variables affect the likelihood of being a supplier instead of a buyer. The way that my model is structured nowthis part of the nest is shown in my stata output with no problem. However, I am having problem with my second level, I would like the output to show how some alternative specific variables affect the likelihood that buyers and suppliers will have an R&D department. So, I want to produce an output in which the first level explains the likelihood of being a buyer or a supplier and second level the likelihood that the buyer will or not have an R&D department and thesupplier will or not have an R&D department. As I mentioned, I am ableto produce an output in which I can observe the first level, but inthe second level instead of comparing buyers that have R&D with buyersthat do not have it (and the same wit! h suppliers), my output shows all the 4 final alternatives in the same model, taking one of them as the baseline. That is the command I am using to build the tree: nlogitgen r&d= final_outcome(buyer_n: 1, buyer_w: 2, supplier_n: 3, supplier_w: 4) nlogitgen buyer_or_supplier= r&d(buyer: buyer_n | buyer_w , supplier: supplier_n | supplier_w) I could not figure out a way to compare only buyers with and without R&D and suppliers with and without R&D in the second level. Any suggestions are more than welcome Very best, Solon * * For searches and help try: * http://www.stata.com/help.cgi?search * http://www.stata.com/support/statalist/faq * http://www.ats.ucla.edu/stat/stata/
-- Sergio Alvarez Food and Resource Economics University of Florida * * For searches and help try: * http://www.stata.com/help.cgi?search * http://www.stata.com/support/statalist/faq * http://www.ats.ucla.edu/stat/stata/