forecast (version 2.01)

forecast.Arima: Forecasting using ARIMA models

Description

Returns forecasts and other information for univariate ARIMA models.

Usage

## S3 method for class 'Arima':
forecast(object, h=ifelse(object$arma[5]>1,2*object$arma[5],10),
    level=c(80,95), fan=FALSE, xreg=NULL,...)
## S3 method for class 'ar':
forecast(object, h=10, level=c(80,95), fan=FALSE, ...)

Arguments

object
An object of class "Arima" or "ar". Usually the result of a call to arima or ar.
h
Number of periods for forecasting. If xreg is used, h is ignored and the number of forecast periods is set to the number of rows of xreg.
level
Confidence level for prediction intervals.
fan
If TRUE, level is set to seq(50,99,by=1). This is suitable for fan plots.
xreg
Future values of an regression variables (for class Arima objects only).
...
Other arguments.

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.Arima. An object of class "forecast" is a list containing at least the following elements:
  • modelA list containing information about the fitted model
  • methodThe name of the forecasting method as a character string
  • meanPoint forecasts as a time series
  • lowerLower limits for prediction intervals
  • upperUpper limits for prediction intervals
  • levelThe confidence values associated with the prediction intervals
  • xThe original time series (either object itself or the time series used to create the model stored as object).
  • residualsResiduals from the fitted model. That is x minus fitted values.
  • fittedFitted values (one-step forecasts)

Details

This function calls predict.arima or predict.ar and constructs an object of class "forecast" from the results.

See Also

predict.arima, ar, arima, rwf.

Examples

Run this code
fit <- Arima(WWWusage,c(3,1,0))
plot(forecast(fit))

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