R: Forecasting using Holt-Winters objects

forecast.HoltWinters {forecast} | R Documentation

## Forecasting using Holt-Winters objects

### Description

Returns forecasts and other information for univariate Holt-Winters time series models.

### Usage

    ## S3 method for class 'HoltWinters'
    forecast(
      object,
      h = ifelse(frequency(object$x) > 1, 2 * frequency(object$x), 10),
      level = c(80, 95),
      fan = FALSE,
      lambda = NULL,
      biasadj = NULL,
      ...
    )

### Arguments

`object` | An object of class "`HoltWinters`". Usually the result of a call to `HoltWinters`.
`h` | Number of periods for forecasting
`level` | Confidence level for prediction intervals.
`fan` | If TRUE, level is set to seq(51,99,by=3). This is suitable for fan plots.
`lambda` | Box-Cox transformation parameter. If `lambda="auto"`, then a transformation is automatically selected using `BoxCox.lambda`. The transformation is ignored if NULL. Otherwise, data transformed before model is estimated.
`biasadj` | Use adjusted back-transformed mean for Box-Cox transformations. If transformed data is used to produce forecasts and fitted values, a regular back transformation will result in median forecasts. If biasadj is TRUE, an adjustment will be made to produce mean forecasts and fitted values.
`...` | Other arguments.

### Details

This function calls `predict.HoltWinters` and constructs an object of class "`forecast`" from the results.

It is included for completeness, but the `ets` is recommended for use instead of `HoltWinters`.

### Value

An object of class "`forecast`".

The function `summary` is used to obtain and print a summary of the results, while the function `plot` produces a plot of the forecasts and prediction intervals.

The generic accessor functions `fitted.values` and `residuals` extract useful features of the value returned by `forecast.HoltWinters`.

An object of class `"forecast"` is a list containing at least the following elements:

`model` | A list containing information about the fitted model
`method` | The name of the forecasting method as a character string
`mean` | Point forecasts as a time series
`lower` | Lower limits for prediction intervals
`upper` | Upper limits for prediction intervals
`level` | The confidence values associated with the prediction intervals
`x` | The original time series (either `object` itself or the time series used to create the model stored as `object`).
`residuals` | Residuals from the fitted model.
`fitted` | Fitted values (one-step forecasts)

### Author(s)

Rob J Hyndman

### See Also

`predict.HoltWinters`, `HoltWinters`.

### Examples

    fit <- HoltWinters(WWWusage,gamma=FALSE)
    plot(forecast(fit))

[Package forecast version 8.12 Index]