Sorry there was a typo in my previous reply:
> D50 <- 10^c(logD50 + c(0, -1.96, 1.96) * attr(logD50, "SE"))
> names(D50) <- c("D50", "lower", "upper")
> D50
D50 lower upper
140.8353 103.3171 191.9777
Best,
Renaud
2006/8/21, Renaud Lancelot <[EMAIL PROTECTED]>:
> I don't know what Finney's fiducial confidence interval is but if your
> problem is to handle the output of dose.p (from MASS), you can do as
> follows:
>
> > library(MASS)
> > Response <- c(0, 7, 26, 27, 0, 5, 13, 29, 0, 4, 11, 25)
> > Tot <- rep(30.5, 12)
> > Dose <- rep(c(10, 40, 160, 640), 3)
> > fm <- glm(Response/Tot ~ log10(Dose), family = quasibinomial(link = probit))
> > logD50 <- dose.p(fm, cf = 1:2, p = 0.5)
> > D50 <- 10^c(logD50 + c(1, -1.96, 1.96) * attr(logD50, "SE"))
> > names(D50) <- c("D50", "lower", "upper")
> > D50
> D50 lower upper
> 164.9506 103.3171 191.9777
>
> Best,
>
> Renaud
>
> 2006/8/21, carlos riveira <[EMAIL PROTECTED]>:
> > I am working with Probit regression (I cannot switch to logit) can
> > anybody help me in finding out how to obtain with R Finney's fiducial
> > confidence intervals for the levels of the predictor (Dose) needed to
> > produce a proportion of 50% of responses(LD50, ED50 etc.)?
> > If the Pearson chi-square goodness-of-fit test is significant (by
> > default), a heterogeneity factor should be used to calculate the limits.
> >
> > Response<-c(0,7,26,27,0,5,13,29,0,4,11,25)
> > Tot<-rep(30.5,12)
> > Dose<-rep(c(10,40,160,640),3)
> > probit<-glm(formula = Response/Tot~ log10(Dose), family=quasibinomial
> > (link=probit))
> > D50<- round(10^(dose.p(probit,cf=1:2,p=0.5)))
> >
> > #This is what SPSS calculates. I would like to reproduce these results
> > with R:
> > #SPSS RESULTS:
> > #PRNT50= 140,83525
> > #CI = 98,37857;205,34483
> > #Regr.coeff= 1,91676 (S.E.=0,16765)
> > #Intercept=-4,11856 (S.E.=0,36355)
> > Thanks a lot for your help.
> >
> > Carlos
> >
> > __________________________________________________
> >
> >
> >
> > [[alternative HTML version deleted]]
> >
> > ______________________________________________
> > [email protected] 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.
> >
>
>
> --
> Renaud LANCELOT
> Département Elevage et Médecine Vétérinaire (EMVT) du CIRAD
> Directeur adjoint chargé des affaires scientifiques
>
> CIRAD, Animal Production and Veterinary Medicine Department
> Deputy director for scientific affairs
>
> Campus international de Baillarguet
> TA 30 / B (Bât. B, Bur. 214)
> 34398 Montpellier Cedex 5 - France
> Tél +33 (0)4 67 59 37 17
> Secr. +33 (0)4 67 59 39 04
> Fax +33 (0)4 67 59 37 95
>
--
Renaud LANCELOT
Département Elevage et Médecine Vétérinaire (EMVT) du CIRAD
Directeur adjoint chargé des affaires scientifiques
CIRAD, Animal Production and Veterinary Medicine Department
Deputy director for scientific affairs
Campus international de Baillarguet
TA 30 / B (Bât. B, Bur. 214)
34398 Montpellier Cedex 5 - France
Tél +33 (0)4 67 59 37 17
Secr. +33 (0)4 67 59 39 04
Fax +33 (0)4 67 59 37 95
______________________________________________
[email protected] 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.
