Introduced on day 23
Seasonal naive
A forecast equal to the observation from the same season in the previous cycle, such as the same weekday last week or the same month last year.
In detail
Seasonal naive has no parameters to fit, so it cannot overfit, and it encodes the one structure that most business series visibly have. It is the standard benchmark for seasonal data: a model that cannot beat it on the same origins and horizons has not shown it adds value. It copies the trend-free past, so it lags a series that grows steadily by about one cycle of growth.