forecast
Forecast future values
Description
Forecast future values
Usage
forecast(x, M, a, h = 10, opt = 2, alpha = 0.05)
Arguments
x
Time series data
M
Data model
a
ARMA model
h
Steps ahead
opt
Display option (0 silent, 1 tabulate, 2 plot and tabulate)
alpha
Level of significance
Details
The data model can be NULL for none. Otherwise M is a vector of function names and arguments.
Example:
M = c("log","season",12,"trend",1)
The above model takes the log of the data, then subtracts a seasonal component of period 12, then
subtracts a linear trend component.
These are the available functions:
diff
Difference the data. Has a single argument, the lag.
hr
Subtract harmonic components. Has one or more arguments, each specifying the number of observations per harmonic.
log
Take the log of the data, has no arguments.
season Subtract a seasonal component. Has a single argument, the number of observations per season.
trend
Subtract a trend component. Has a single argument, the order of the trend (1 linear, 2 quadratic, etc.)