R: Bollinger Bands

BBands {TTR} | R Documentation

## Bollinger Bands

### Description

Bollinger Bands are a way to compare a security's volatility and price levels over a period of time. Developed by John Bollinger.

### Usage

    BBands(HLC, n = 20, maType, sd = 2, ...)

### Arguments

`HLC` | Object that is coercible to xts or matrix and contains High-Low-Close prices. If only a univariate series is given, it will be used. See details.
`n` | Number of periods for moving average.
`maType` | A function or a string naming the function to be called.
`sd` | The number of standard deviations to use.
`...` | Other arguments to be passed to the `maType` function.

### Details

Bollinger Bands consist of three lines:

The middle band is generally a 20-period SMA of the typical price ([high + low + close]/3). The upper and lower bands are `sd` standard deviations (generally 2) above and below the MA.

The middle band is usually calculated using the typical price, but if a univariate series (e.g. Close, Weighted Close, Median Price, etc.) is provided, it will be used instead.

### Value

A object of the same class as `HLC` or a matrix (if `try.xts` fails) containing the columns:

dn

  The lower Bollinger Band.

mavg

  The middle Moving Average (see notes).

up

  The upper Bollinger Band.

pctB

  The %B calculation.

### Note

Using any moving average other than SMA will result in inconsistencies between the moving average calculation and the standard deviation calculation. Since, by definition, a rolling standard deviation uses a simple moving average.

### Author(s)

Joshua Ulrich

### References

The following site(s) were used to code/document this indicator:
http://www.fmlabs.com/reference/Bollinger.htm
http://www.fmlabs.com/reference/BollingerWidth.htm
http://www.equis.com/Customer/Resources/TAAZ/?c=3&p=36
http://www.linnsoft.com/tour/techind/bb.htm
http://stockcharts.com/education/IndicatorAnalysis/indic_Bbands.html
http://stockcharts.com/education/IndicatorAnalysis/indic_BBWidth.htm

### See Also

See `EMA`, `SMA`, etc. for moving average options; and note Warning section.

### Examples

    ## The examples below show the differences between using a
    ## High-Low-Close series, and just a close series when
    ## calculating Bollinger Bands.
    data(ttrc)
    bbands.HLC <- BBands( ttrc[,c("High","Low","Close")] )
    bbands.close <- BBands( ttrc[,"Close"] )

[Package TTR version 0.23-1 Index]