drc (version 1.2-0)

daphnids: Daphnia test

Description

The number of immobile daphnids --in contrast to mobile daphnids-- out of a total of 20 daphnids was counted for several concentrations of a toxic substance.

Usage

data(daphnids)

source

Nina Cedergreen, Faculty of Life Sciences, University of Copenhagen, Denmark.

Details

The same daphnids were counted at 24h and later again at 48h.

Examples

## Fitting a model with different parameters
##  for different curves
##  using 'multdrc'
daphnids.m1 <- multdrc(no/total~dose, time, weights=total, 
data=daphnids, fct=l2(), type="binomial")

summary(daphnids.m1)

## Goodness-of-fit test
anova(daphnids.m1)

## Fitting a model with a common intercept parameter
##  using 'multdrc'
daphnids.m2 <- multdrc(no/total~dose, time, weights=total, 
data=daphnids, fct=l2(), type="binomial", 
collapse=list(~1, ~time))

## The same fits using 'drm'
daphnids.m1 <- drm(no/total~dose, time, weights=total, 
data=daphnids, fct=LL.2(), type="binomial")

daphnids.m2 <- drm(no/total~dose, time, weights=total, 
data=daphnids, fct=LL.2(), type="binomial", 
pmodels=list(~1, ~time))