aTSA (version 3.1.2)

# forecast: Forecast From ARIMA Fits

## Description

Forecasts from models fitted by arima or estimate function.

## Usage

forecast(object, lead = 1, id = NULL, alpha = 0.05, output = TRUE)

## Arguments

object
the result of an arima or estimate fit.
lead
the number of steps ahead for which prediction is required. The default is 1.
id
the id of the observation which is the time. The default is NULL.
alpha
the significant level for constructing the confidence interval of prediction. The default is 0.05.
output
a logical value indicating to print the results in R console. The default is TRUE.

## Value

A matrix with lead rows and five columns. Each column represents the number of steps ahead (Lead), the predicted values (Forecast), the standard errors (S.E) and the 100*(1 - $\alpha$)% lower bound (Lower) and upper bound (Upper) of confidence interval.

## Details

This function is originally from predict.Arima in stats package, but has a nice output including 100*(1 - $\alpha$)% confidence interval and a prediction plot. It is similar to FORECAST statement in PROC ARIMA of SAS.

## See Also

predict.Arima

## Examples

x <- arima.sim(list(order = c(3,0,0),ar = c(0.2,0.4,-0.15)),n = 100)
fit <- estimate(x,p = 3) # same as fit <- arima(x,order = c(3,0,0))
forecast(fit,lead = 4)

# forecast with id
t <- as.Date("2014-03-25") + 1:100
forecast(fit,lead = 4, id = t)