Daphnia test

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.

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

# NOT RUN {
library(drc)

## 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))
# }