data-budworm: budworm data

Description Usage Format Source References Examples

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

1

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

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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)

doBy documentation built on Aug. 30, 2018, 9:03 a.m.