# width.SJ

From MASS v7.3-19
by Brian Ripley

##### Bandwidth Selection by Pilot Estimation of Derivatives

Uses the method of Sheather & Jones (1991) to select the bandwidth of a Gaussian kernel density estimator.

- Keywords
- dplot

##### Usage

`width.SJ(x, nb = 1000, lower, upper, method = c("ste", "dpi"))`

##### Arguments

- x
- a numeric vector
- nb
- number of bins to use.
- upper, lower
- range over which to search for solution if
`method = "ste"`

. - method
- Either
`"ste"`

("solve-the-equation") or`"dpi"`

("direct plug-in").

##### Value

- a bandwidth.

##### References

Sheather, S. J. and Jones, M. C. (1991) A reliable data-based bandwidth
selection method for kernel density estimation.
*Journal of the Royal Statistical Society series B*
**53**, 683--690.

Scott, D. W. (1992)
*Multivariate Density Estimation: Theory, Practice, and Visualization.*
Wiley.

Wand, M. P. and Jones, M. C. (1995)
*Kernel Smoothing.*
Chapman & Hall.

##### See Also

##### Examples

```
attach(geyser)
width.SJ(duration, method = "dpi")
width.SJ(duration)
detach()
width.SJ(galaxies, method = "dpi")
width.SJ(galaxies)
```

*Documentation reproduced from package MASS, version 7.3-19, License: GPL-2 | GPL-3*

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