[R] mob(party) formula question

[Achim Zeileis]

On Wed, 13 Aug 2008, Birgitle wrote:

> Many thanks for your answer and the code that you offered me.
>
> I get this error message after calling mob (look at my given example).
> I guess it has something to do with the missings?

Yes, you have to handle NAs in advance if you want to fit that model. 
We'll try to fix that in future versions.

> The iris example works also fine for me.
>
> Sorry that I am not enough into statistics to really understand the
> following:
>
>
> Achim Zeileis wrote:
>>
>>
>> .....
>> For the variables for which a linear specification makes sense (at least
>> in each component) then you should include them for modeling. And those
>> variables for which it is not clear a priori what a useful parametric
>> specification would be should be used as partitioning variables.
>> ...
>>
>>
>
> What do you mean with "linear specification"? I would be very happy if you
> could explain.

Well, in each node you fit a logistic regression model. This is a 
(generalized) linear model, hence the variables included have a linear 
influence (on the link scale) within each node. The partitioning variables 
on the other hand capture step-shaped influences (if they are selected by 
the algorithm). See the references on ?mob for further details.

Best,
Z