A statistical model is used in applied statistics. Three basic notions are sufficient to describe all statistical models.
We choose a statistical unit which we will observe directly. Multiple observations of the same unit over time is called longitudinal research[?]. Observations of a variety of statistical attributes[?] is a common way of studying relationships among the attributes of a single unit.
We may really be interested in a statistical population (or set) of similar units rather than in any statistical unit per se. Survey sampling offers an example of this type of application.
... the morphological groups are clear:
ORDER GALLIFORMES
Family Megapodiidae
Scrubfowl group[?]: Megapodius (11 species) and Macrocephalon (1 species).
Maleo, ...