r.bw {asbio} | R Documentation |

## Biweight midvariance, and biweight midcorrelation.

### Description

Calculates biweight midvariance if one variable is given and biweight midvariances, midcovariance and midcorrelation if two variables are given. Biweight midcorrelation is a robust alternative to Pearson's *r*.

### Usage

```
r.bw(X, Y=NULL)
```

### Arguments

`X` |
A numeric vector |

`Y` |
An optional second numeric variable. |

### Details

Biweight statistics are robust to violations of normality. Like the sample median the sample midvariance has a breakdown point of approximately 0.5. The triefficiency of the biweight midvariance was the highest for any of the 150 measures of scale compared by Lax (1985).

### Value

Returns the biweight variance if one variable is given, and the biweight midvariances, midcovariance and midcorrelation if two variables are given.

### Author(s)

Ken Aho

### References

Lax, D. A. (1985) Robust estimators of scale: finite sample performance in long-tailed symmetric distributions. *Journal of the American Statistical Association*, 80 736-741.

Wilcox, R. R. (2005) *Introduction to Robust Estimation and Hypothesis Testing, Second Edition*. Elsevier, Burlington, MA.

### See Also

### Examples

```
x<-rnorm(100)
y<-rnorm(100)
r.bw(x,y)
```

*asbio*version 1.9-7 Index]