hbk {rrcov} | R Documentation |

## Hawkins, Bradu, Kass's Artificial Data

### Description

Artificial Data Set generated by Hawkins, Bradu, and Kass (1984).
The data set consists of 75 observations in four dimensions
(one response and three explanatory variables). It provides a
good example of the masking effect. The first 14
observations are outliers, created in two groups: 1-10 and 11-14.
Only observations 12, 13 and 14 appear as outliers when using
classical methods, but can be easily unmasked using robust
distances computed by e.g. MCD - covMcd().

### Usage

data(hbk)

### Format

A data frame with 75 observations on 4 variables, where the last variable is the dependent one.

For convenience, the data sets `hbk.x`

, a matrix with the three (independent) variables of the data frame, and `hbk.y`

, the numeric vector giving the fourth (dependent) variable, are provided as well.

### Source

Hawkins, D.M., Bradu, D., and Kass, G.V. (1984)
Location of several outliers in multiple regression data using elemental sets.
*Technometrics,*
**26**, 197–208.

### See Also

P. J. Rousseeuw and A. M. Leroy (1987)
*Robust Regression and Outlier Detection.* Wiley, p.94.

### Examples

data(hbk)
plot(hbk.x)
covMcd(hbk.x)
summary(lm.hbk <- lm(hbk.y ~ hbk.x))

[Package

*rrcov* version 0.2-5

Index]