Forecasting within limits

It is common to want forecasts to be positive, or to require them to be within some specified range ([a,b]). Both of these situations are relatively easy to handle using transformations.Positive forecasts To impose a positivity constraint, simply work on the log scale. With the forecast package in R, this can be handled by specifying the Box-Cox parameter (\lambda=0). For example, consider the real price of a dozen eggs (1900-1993; in …