data-budworm {pbkrtest} | R Documentation |
Effect of Insecticide on survivial of tobacco budworms number of killed budworms exposed to an insecticidepp mortality of the moth tobacco budworm 'Heliothis virescens' for 6 doses of the pyrethroid trans-cypermethrin differentiated with respect to sex
budworm
This data frame contains 12 rows and 4 columns:
sex of the budworm
dose of the insecticide trans-cypermethrin in [mug]
budworms killed in a trial
total number of budworms exposed per trial
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)) ## Not run: * SAS example; data budworm; infile 'budworm.txt' firstobs=2; input sex dose ndead ntotal; run; ## End(Not run)