Data-generating process (DGP)
We saw that time series data is a collection of observations made sequentially along the time dimension. Any time series is, in turn, generated by some kind of mechanism. For example, time series data of daily shipments of your favorite chocolate from the manufacturing plant is affected by a lot of factors such as the time of the year, the holiday season, the availability of cocoa, the uptime of the machines working on the plant, and so on. In statistics, this underlying process that generated the time series is referred to as the DGP. Time series data is produced by stochastic and deterministic process. The deterministic processes involve quantities that evolve in a predictable manner over time. An example of this is the radioactive decay of an element, where the remaining quantity diminishes according to a precise mathematical formula, leading to a consistent reduction over time. But most of the interesting time series (from a forecasting perspective) are...