Main Page | See live article | Alphabetical index 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. Our interest may be focused on a statistical assembly where we examine functional subunits of the statistical unit. Physiology is an example in which we probe the organs which compose the unit. A common model for this type of research is the stimulus-response model. This article is from Wikipedia. All text is available under the terms of the GNU Free Documentation License.