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.

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.

Examples

Run this code

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

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