thanks for the hint, Kjetil. That looks more like what I am looking for. Thanks for all your mails! Best, Stefan
On Wed, Jun 8, 2011 at 11:25 PM, Kjetil Halvorsen <kjetilbrinchmannhalvor...@gmail.com> wrote: > see inline below. > > On Wed, Jun 8, 2011 at 12:37 PM, Anupam <anupa...@gmail.com> wrote: >> It is difficult for someone from a statistical frame of mind to understand >> what this is about --- you need to think a bit differently. It is mostly a >> simulation and decision analysis, with some use of statistical functions to >> draw random samples to simulate the fact that outcome of interest can take >> any value from a known or unknown distribution. For example, you may be >> comparing two interventions and a do-nothing decision to improve some health >> outcome of interest. The decision maker is interested in *relative* >> effectiveness and costs of the interventions to improve the outcome of >> interest. You have results from published literature that you can use as >> inputs into a simulation exercise to compare relative costs and >> benefits/effectiveness of the three options. A small decision tree can be >> easily simulated in a spreadsheet; for long trees with many decision nodes >> it is useful to have a specialized software. There are some Excel plugins >> that are sold about $100. Others are more expensive. >> >> I think R is not well suited for this kind of work. A decision analysis > > Not necessarily! A desicion tree model is a kind of graphical model. > See the CRAN task view gR > (graphical models in R) and maybe ask on the special interest mailing > list R-sig-gR > > kjetil > >> package in R may require user to write code like the one used in LaTeX or >> related programs (Metapost) to draw graphs of trees (e.g. complicated >> organizational trees, or hierarchical trees). However, in such a package >> there can be useful outputs, measures and graphs generated by R using code >> that may already exist for other packages. >> >> Look up journal "Medical Decision Making" to know what is being discussed. >> This method is used extensively in medicine and public health to study >> decisions. It even uses MCMC, though with a different flavor --- it may even >> be a different kind of food. >> >> Anupam. >> -----Original Message----- >> From: r-help-boun...@r-project.org [mailto:r-help-boun...@r-project.org] On >> Behalf Of Jonathan Daily >> Sent: Wednesday, June 08, 2011 7:47 PM >> To: stefan.d...@gmail.com >> Cc: r-help@r-project.org >> Subject: Re: [R] Decision Trees /Decision Analysis with R? >> >> So TreeAge fits models but won't predict from them? That seems like bizarre >> behavior. I suppose I would recommend, then, looking at the source code from >> the aforementioned packages for how they store their split data. It sounds >> like you would have to write code to hack TreeAge outputs into another >> packages' format (e.g. look at ?rpart.object). >> >> Sorry I couldn't help more, >> Jon >> >> On Wed, Jun 8, 2011 at 9:47 AM, stefan.d...@gmail.com >> <stefan.d...@gmail.com> wrote: >>> Thank you so much for reply. But I am looking for the exact opposite. >>> >>> I do not have a data set which I want to partition. But already a >>> sequence/tree-like set of decision rules and with which I want to >>> simulate what is my expected outcome/pay-off given a particular >>> scenario. >>> As far as I understand it, those packages could calculate the expected >>> outcome AFTER having fit them to a particular data set and not >>> construct a "synthetic" tree with exogenously defined decision >>> nods/rules. Or am I wrong? >>> >>> >>> Thanks and best, >>> Stefan >>> >>> >>> >>> On Wed, Jun 8, 2011 at 2:03 PM, Jonathan Daily <biomathjda...@gmail.com> >> wrote: >>>> See packages rpart, randomForest, party. >>>> >>>> Also, typing "R Decision Trees" produced good google results. >>>> >>>> http://www.google.com/search?aq=f&sourceid=chrome&ie=UTF-8&q=R+Decisi >>>> on+Trees >>>> >>>> On Wed, Jun 8, 2011 at 7:02 AM, stefan.d...@gmail.com >>>> <stefan.d...@gmail.com> wrote: >>>>> Hello, >>>>> >>>>> this question is a bit out of the blue. >>>>> >>>>> I am a big R fan and user and in my new job I do some decision >>>>> modeling (mostly health economics). For that decision trees are >>>>> often used (I guess the most classic example is the investment >>>>> decision A, B, and C with different probabilities, what is the expected >> payoff). >>>>> We use a specialized software called TreeAge that some might know. >>>>> The basic setup of such simulations is actually very simple and I >>>>> guess useful in many fields. So I was wondering whether there is >>>>> already a package out there in R that is doing such a thing? >>>>> >>>>> Thanks for any hints! >>>>> Best, >>>>> Stefan >>>>> >>>>> PS >>>>> (By decision tree I don't mean cluster-like analysis of a data set >>>>> splitting by identifying decision nods, but the other way around: I >>>>> have decision nodes, what is my expected outcome.) >>>>> >>>>> ______________________________________________ >>>>> R-help@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. >>>>> >>>> >>>> >>>> >>>> -- >>>> =============================================== >>>> Jon Daily >>>> Technician >>>> =============================================== >>>> #!/usr/bin/env outside >>>> # It's great, trust me. >>>> >>> >> >> >> >> -- >> =============================================== >> Jon Daily >> Technician >> =============================================== >> #!/usr/bin/env outside >> # It's great, trust me. >> >> ______________________________________________ >> R-help@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. >> >> ______________________________________________ >> R-help@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. >> > ______________________________________________ R-help@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.
