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From |
Solon Moreira <sm.ino@cbs.dk> |

To |
"statalist@hsphsun2.harvard.edu" <statalist@hsphsun2.harvard.edu> |

Subject |
RE: st: nested logit tree |

Date |
Mon, 28 Nov 2011 17:33:59 +0100 |

Hi Sergio, Thanks for your email. In fact I want a decision model that has 4 possible outcomes: a buyer with R&D, a buyer without R&D, a supplier with R&D and a supplier without R&D. So in the end I have 4 possible alternatives in my data. I had a look in the restaurant data, but it is not exactly what I want, I think I need 2 levels. I could also calculate different logit models but I am not sure that is the best solution. I am expecting that the effect of some of my covariates will have a different direction in affecting the likelyhood of a firm having R&D or not depending on the side of the market that it it (buyer of supplier). Thanks, Solon ________________________________________ From: owner-statalist@hsphsun2.harvard.edu [owner-statalist@hsphsun2.harvard.edu] On Behalf Of Alvarez,Sergio [sergioal@ufl.edu] Sent: Monday, November 28, 2011 5:02 PM To: statalist@hsphsun2.harvard.edu Subject: Re: st: nested logit tree 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 sell > technologies. 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 > now > this 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 the > supplier will or not have an R&D department. As I mentioned, I am > able > to produce an output in which I can observe the first level, but in > the second level instead of comparing buyers that have R&D with > buyers > that 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/ * * 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/

**Follow-Ups**:**RE: st: nested logit tree***From:*"Alvarez,Sergio" <sergioal@ufl.edu>

**References**:**st: nested logit tree***From:*Solon Moreira <sm.ino@cbs.dk>

**Re: st: nested logit tree***From:*"Alvarez,Sergio" <sergioal@ufl.edu>

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