Hello, we are needing to generate optimal (Fractional) designs for discrete choice applications, where we will be using logistic regression or multinomial logit as the modeling technique. It looks like optFederov, in the AlgDesign package may work, but not sure if this algorithm works when the variable of interest is binary or nominal? Anyone who are experts in this area, anyone interested in consulting with us in this topic (if so, email me we can arrange)? Or can confirm/deny optFederov can work in the discrete case? thx!
I would suggest reading this attachment below. http://support.sas.com/techsup/technote/ts722d.pdf OptFedreov is the go for you, you are correct. I don't know of anybody who has come up with design principles in choice modelling that apply to logit and probit models etc. We all assume that what is good for linear models in principle, is also good for choice models, even when the utilities we are estimating are non-linear. I think it is important to recognise that d-efficiency is the best method of evaluation for choice designs and you should be aiming for an orthogonal array in your design as suggested in this article if you are using traditional logit and MNL, please make sure you allow enough choices and enough cases to complete the choices, and also that your algorithms are geared towards repeated choices if you are using a stated preference approach where people are answering a number of choice alternatives Bob Wheeler may be able to comment further, but i think you are on the right track Thanks Paul ----- Original Message ----- From: "zubin" <binabina at bellsouth.net> To: <r-help at r-project.org> Sent: Monday, April 21, 2008 9:59 PM Subject: [R] optFederov/AlgDesign - help avail?> Hello, we are needing to generate optimal (Fractional) designs for > discrete choice applications, where we will be using logistic regression > or multinomial logit as the modeling technique. > > It looks like optFederov, in the AlgDesign package may work, but not > sure if this algorithm works when the variable of interest is binary or > nominal? > > Anyone who are experts in this area, anyone interested in consulting > with us in this topic (if so, email me we can arrange)? > > Or can confirm/deny optFederov can work in the discrete case? > > thx! > > ______________________________________________ > R-help at r-project.org mailing list > https://stat.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide > http://www.R-project.org/posting-guide.html > and provide commented, minimal, self-contained, reproducible code. >
of yeah, and your design needs to account for main effects and interactions if you intend to model them, so make sure to program that into algdesign as well ----- Original Message ----- From: "zubin" <binabina at bellsouth.net> To: <r-help at r-project.org> Sent: Monday, April 21, 2008 9:59 PM Subject: [R] optFederov/AlgDesign - help avail?> Hello, we are needing to generate optimal (Fractional) designs for > discrete choice applications, where we will be using logistic regression > or multinomial logit as the modeling technique. > > It looks like optFederov, in the AlgDesign package may work, but not > sure if this algorithm works when the variable of interest is binary or > nominal? > > Anyone who are experts in this area, anyone interested in consulting > with us in this topic (if so, email me we can arrange)? > > Or can confirm/deny optFederov can work in the discrete case? > > thx! > > ______________________________________________ > R-help at r-project.org mailing list > https://stat.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide > http://www.R-project.org/posting-guide.html > and provide commented, minimal, self-contained, reproducible code. >
Hi, The design generated using optFederov is not including all the levels ie levels are missing from the fractional factorial design. Can anyone plz help with the modified command. The command i am giving is- library(AlgDesign) Levels.design=c(3,4,2) fe.design<-gen.factorial(levels.design) fe.design met.design <- optFederov( data=fe.design, nTrials=10, criterion="D", maxIteration=100, approximate=FALSE) met.design Thanks -- View this message in context: http://r.789695.n4.nabble.com/optFederov-AlgDesign-help-avail-tp857129p4634170.html Sent from the R help mailing list archive at Nabble.com.