[R] Decision Trees /Decision Analysis with R?

[stefan.duke at gmail.com]

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
<kjetilbrinchmannhalvorsen at gmail.com> wrote:
> see inline below.
>
> On Wed, Jun 8, 2011 at 12:37 PM, Anupam <anupamtg at 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-bounces at r-project.org [mailto:r-help-bounces at r-project.org] On
>> Behalf Of Jonathan Daily
>> Sent: Wednesday, June 08, 2011 7:47 PM
>> To: stefan.duke at gmail.com
>> Cc: r-help at 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.duke at gmail.com
>> <stefan.duke at 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 <biomathjdaily at 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.duke at gmail.com
>>>> <stefan.duke at 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 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.
>>>>>
>>>>
>>>>
>>>>
>>>> --
>>>> ===============================================
>>>> 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 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.
>>
>> ______________________________________________
>> 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.
>>
>