Bounds for the predicted values

[edumucelli]

Hi, I have been using robets for a while (thanks for the lib!) and would like to know whether it is possible to limit the bounds of the forecast results. Imagine I am willing to forecast a value that should never be negative. It would be interesting to have a parameter to control the result given knowledge a priori.

Currently I am trying to predict the number of visits to a given site, but certain results are negative.

Cheers,

[RubenCrevits]

Thanks for your comment. Currently there is no direct way to bound the forecasts, just as with the function ets of the forecast library.

One way to solve your problem is to apply a logarithmic transformation by adding the argument 'lambda = 0' to your robets call. The time series is then first transformed, then a forecast is made based on the transformed series, and then the forecasts are transformed back. This results in forecasts that are always positive.

Kind regards,

Ruben Crevits.