budworm {doBy} | R Documentation |
Number of killed budworms after exposure to an insecticide.
data(budworm)
This data frame contains 12 rows and 4 columns:
sex of the budworm
dose of the insecticide trans-cypermethrin in micro g
budworms killed in a trial
total number of budworms exposed per trial
Mortality of the moth tobacco budworm 'Heliothis virescens' for 6 doses of the pyrethroid trans-cypermethrin differentiated with respect to sex.
Collet, D. (1991) Modelling Binary Data, Chapman & Hall, London, Example 3.7
Venables, W.N; Ripley, B.D.(1999) Modern Applied Statistics with S-Plus, Heidelberg, Springer, 3rd edition, chapter 7.2
data(budworm) ## function to caclulate the empirical logits empirical.logit<- function(nevent,ntotal) { y<-log ((nevent+0.5)/(ntotal-nevent+0.5)) y } ## plot the empirical logits against log-dose log.dose <- log(budworm$dose) emp.logit <- empirical.logit(budworm$ndead,budworm$ntotal) plot(log.dose,emp.logit,type='n',xlab='log-dose',ylab='emprirical logit') title('budworm: emprirical logits of probability to die ') male <- budworm$sex=='male' female <- budworm$sex=='female' lines(log.dose[male],emp.logit[male],type='b',lty=1,col=1) lines(log.dose[female],emp.logit[female],type='b',lty=2,col=2) legend(0.5,2,legend=c('male','female'),lty=c(1,2),col=c(1,2))