# width.SJ

##### 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.

##### Note

A faster version for large `n`

(thousands) is available in R
\(\ge\) 3.4.0 as part of `bw.SJ`

: quadruple its
value for comparability with this version.

##### 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

```
# NOT RUN {
width.SJ(geyser$duration, method = "dpi")
width.SJ(geyser$duration)
width.SJ(galaxies, method = "dpi")
width.SJ(galaxies)
# }
```

*Documentation reproduced from package MASS, version 7.3-51.5, License: GPL-2 | GPL-3*