R: Effect of Insecticide on survivial of tobacco budworms

budworm {doBy} | R Documentation

## Effect of Insecticide on survivial of tobacco budworms

### Description

Number of killed budworms after exposure to an insecticide.

### Usage

    data(budworm)

### Format

This data frame contains 12 rows and 4 columns:

sex:

  sex of the budworm

dose:

  dose of the insecticide trans-cypermethrin in micro g

ndead:

  budworms killed in a trial

ntotal:

  total number of budworms exposed per trial

### Details

Mortality of the moth tobacco budworm 'Heliothis virescens' for 6 doses of the pyrethroid trans-cypermethrin differentiated with respect to sex.

### Source

Collet, D. (1991) Modelling Binary Data, Chapman & Hall, London, Example 3.7

### References

Venables, W.N; Ripley, B.D.(1999) Modern Applied Statistics with S-Plus, Heidelberg, Springer, 3rd edition, chapter 7.2

### Examples

    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))

[Package doBy version 4.5-15 Index]