Statistical unit

related topics
{math, energy, light}
{theory, work, human}
{rate, high, increase}
{disease, patient, cell}
{system, computer, user}
{company, market, business}
{mi², represent, 1st}

A unit in a statistical analysis refers to one member of a set of entities being studied. It is the material source for the mathematical abstraction of a "random variable". Common examples of a unit would be a single person, animal, plant, or manufactured item that belongs to a larger collection of such entities being studied.

Units are often referred to as being either experimental units, sampling units or, more generally, units of observation:

  • An "experimental unit" is typically thought of as one member of a set of objects that are initially equivalent, with each object then subjected to one of several experimental treatments.

In most statistical studies, the goal is to generalize from the observed units to a larger set consisting of all comparable units that exist but are not directly observed. For example, if we randomly sample 100 people and ask them which candidate they intend to vote for in an election, our main interest is in the voting behavior of all eligible voters, not exclusively on the 100 observed units.

In some cases, the observed units may not form a sample from any meaningful population, but rather constitute a convenience sample, or may represent the entire population of interest. In this situation, we may study the units descriptively, or we may study their dynamics over time. But it typically does not make sense to talk about generalizing to a larger population of such units. Studies involving countries or business firms are often of this type.

In simple data sets, the units are in one-to-one correspondence with the data values. In more complex data sets, multiple measurements are made for each unit. For example, if blood pressure measurements are made daily for a week on each subject in a study, there would be seven data values for each statistical unit.

While a unit is often the lowest level at which observations are made, in some cases, a unit can be further decomposed as a statistical assembly.

Many statistical analyses use quantitative data that have units of measurement. This is a distinct and non-overlapping use of the term "unit."

Contents

See also

Bibliography

Design of experiments

Full article ▸

related documents
Francis Baily
List of satellites which have provided data on Earth's magnetosphere
International Commission on Illumination
Giulio Racah
Laws of science
Harold Furth
Franz Xaver von Zach
Domenico Maria Novara da Ferrara
Antlia
International Earth Rotation and Reference Systems Service
La Jeunesse
ICOMP
Revolt in 2100
Gerhard Gentzen
Pineville
Vlagtwedde
Shannara family tree
List of cities in Germany
River Little Stour
George H. Tichenor
National Party
Beckman Research Institute
Mendel University of Agriculture and Forestry Brno
United States Secretary of Health, Education, and Welfare
Doomsday Clock
United States Secretary of Transportation
Communes of the Alpes-de-Haute-Provence department
7th Computer Olympiad
Douro
Barneveld