carrots | 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, package="robustbase")`

### 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)) ....
```