## 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)

### Format

A data frame with 16 observations on the following 4 variables.

`dose`

a numeric vector

`no`

a numeric vector

`total`

a numeric vector

`time`

a factor with levels `24h`

`48h`

### Details

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

### Source

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

### Examples

## Fitting a model with different parameters
## for different curves
daphnids.m1 <- drm(no/total~dose, time, weights = total,
data = daphnids, fct = LL.2(), type = "binomial")
## Goodness-of-fit test
modelFit(daphnids.m1)
## Summary of the data
summary(daphnids.m1)
## Fitting a model with a common intercept parameter
daphnids.m2 <- drm(no/total~dose, time, weights = total,
data = daphnids, fct = LL.2(), type = "binomial",
pmodels = list(~1, ~time))