carrots {robustbase} | R Documentation

## Insect Damages on Carrots

### Description

The damage carrots data set from Phelps (1982) was used by McCullagh and Nelder (1989) in order to illustrate diagnostic techniques because of the presence of an outlier. In a soil experiment trial with three blocks, eight levels of insecticide were applied and the carrots were tested for insect damage.

### Usage

    data(carrots)

### Format

A data frame with 24 observations on the following 4 variables.

success

  integer giving the number of carrots with insect damage.

total

  integer giving the total number of carrots per experimental unit.

logdose

  a numeric vector giving log(dose) values (eight different levels only).

block

  factor with levels `B1` to `B3`

### Source

Phelps, K. (1982). Use of the complementary log-log function to describe doseresponse relationships in insecticide evaluation field trials.
In R. Gilchrist (Ed.), Lecture Notes in Statistics, No. 14. GLIM.82: Proceedings of the International Conference on Generalized Linear Models; Springer-Verlag.

### References

McCullagh P. and Nelder, J. A. (1989) Generalized Linear Models. London: Chapman and Hall.

Eva Cantoni and Elvezio Ronchetti (2001); JASA, and
Eva Cantoni (2004); JSS, see `glmrob`

### Examples

    data(carrots)
    str(carrots)
    plot(success/total ~ logdose, data = carrots, col = as.integer(block))
    coplot(success/total ~ logdose | block, data = carrots)

    ## Classical glm
    Cfit0 <- glm(cbind(success, total-success) ~ logdose + block,
                 data=carrots, family=binomial)
    summary(Cfit0)

    ## Robust Fit (see help(glmrob)) ....

[Package robustbase version 0.92-8 Index]