R: budworm data

budworm {doBy} | R Documentation

## budworm data

### Description

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

### Usage

    budworm

### Format

This data frame contains 12 rows and 4 columns:

sex:

  sex of the budworm

dose:

  dose of the insecticide trans-cypermethrin in [mug]

ndead:

  budworms killed in a trial

ntotal:

  total number of budworms exposed per trial

### 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(y, n) {
       el <- log((y + 0.5) / (n - y + 0.5))
       el
    }

    # 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)

[Package doBy version 4.6.5 Index]