R: Daphnia test

daphnids {drc} | R Documentation

## 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))

[Package drc version 3.0-1 Index]