[R] System of logistics Equations

[Arne Henningsen]

Hi Bernardo,

the systemfit package cannot be used to estimate a system of logistic 
equations.

Arne

On Friday, 20. February 2009 05:19:40, Bernardo Rangel Tura wrote:
> Hi R-masters
>
> I need yours help about a problema in one of may ongoing researchers.
>
> In my research the subjects (20 in total) answer 60 questions (20 type
> G, 20 type S and 20 type P).
>
> Which questions is classified about 3 factor (2 level each) and the
> subject score with 2 scale (not integer value is possible but rare): Val
> range -7 to 7 and other Car range 1 to 7.
>
> This a code to fake database of research
>
> Subj<-rep(1:20,each=60)
> Sti<-rep(c("G","S","P"),40)
> SP<-rep(c("S","P"),60)
> AG<-rep(c("A","P"),60)
> Mer<-rep(c("M","NM"),60)
> Car<-round(runif(120,1,7),0)
> Val<-round(runif(120,-7,7),0)
> base<-data.frame(Subj,Sti,SP,AG,Mer,Car,Val)
>
> In my hypothesis:
>
> logit(Sti=="G") ~ SP+AG+Mer+Car+Val+SP*Car+Mer*Val+AG*Val + errorG
>
> logit(Sti=="S") ~ SP+AG+Mer+Car+Val+SP*Car+Mer*Val+AG*Val + errorS
>
> logit(Sti=="P") ~ SP+AG+Mer+Car+Val+SP*Car+Mer*Val+AG*Val + errorP
>
> I test and the 3 terms of error (errorG,errorS,errorP) is correlated.
>
> So I think useful adjust a system of logistic equations to tread the 3
> equations and in same time to obtain estimatives of effects and
> uncorrelated error terms.
>
>
> The systemfit package fit linear system and non-linear system but is
> possible adjust a logistic system in R?
>
> Thanks in advance
-- 
Arne Henningsen
http://www.arne-henningsen.name/