seasonaldummy returns a matrix of dummy variables suitable for use in Arima, auto.arima or tslm. The last season is omitted and used as the control.

seasonaldummy(x, h = NULL)

seasonaldummyf(x, h)



Seasonal time series: a ts or a msts object


Number of periods ahead to forecast (optional)


Numerical matrix.


seasonaldummyf is deprecated, instead use the h argument in seasonaldummy.

The number of dummy variables is determined from the time series characteristics of x. When h is missing, the length of x also determines the number of rows for the matrix returned by seasonaldummy. the value of h determines the number of rows for the matrix returned by seasonaldummy, typically used for forecasting. The values within x are not used.

See also


# Using seasonal dummy variables month <- seasonaldummy(ldeaths) deaths.lm <- tslm(ldeaths ~ month) tsdisplay(residuals(deaths.lm))
ldeaths.fcast <- forecast(deaths.lm, data.frame(month=I(seasonaldummy(ldeaths,36)))) plot(ldeaths.fcast)
# A simpler approach to seasonal dummy variables deaths.lm <- tslm(ldeaths ~ season) ldeaths.fcast <- forecast(deaths.lm, h=36) plot(ldeaths.fcast)