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Statistical population
 
 
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In statistics
Statistics

Statistics is a Mathematics pertaining to the collection, analysis, interpretation or explanation, and presentation of data. It also provides tools for prediction and forecasting based on data....
, a statistical population is a set of entities concerning which statistical inference
Statistical inference

Inferential statistics or statistical induction comprises the use of statistics to make inferences concerning some unknown aspect of a population....
s are to be drawn, often based on a random sample
Random sample

A sample is a subject chosen from a population for investigation. A random sample is one chosen by a method involving an unpredictable component....
 taken from the population. For example, if we were interested in generalizations about crow
Crow

The true crows are large passerine birds that form the genus Corvus in the family Corvidae. Ranging in size from the relatively small dove-sized jackdaws to the Common Raven of the Holarctic region and Thick-billed Raven of the highlands of Ethiopia, the 40 or so members of this genus occur on all temperate continents and several offsh...
s, then we would describe the set of crows that is of interest. Notice that if we choose a population like all crows, we will be limited to observing crows that exist now or will exist in the future.






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In statistics
Statistics

Statistics is a Mathematics pertaining to the collection, analysis, interpretation or explanation, and presentation of data. It also provides tools for prediction and forecasting based on data....
, a statistical population is a set of entities concerning which statistical inference
Statistical inference

Inferential statistics or statistical induction comprises the use of statistics to make inferences concerning some unknown aspect of a population....
s are to be drawn, often based on a random sample
Random sample

A sample is a subject chosen from a population for investigation. A random sample is one chosen by a method involving an unpredictable component....
 taken from the population. For example, if we were interested in generalizations about crow
Crow

The true crows are large passerine birds that form the genus Corvus in the family Corvidae. Ranging in size from the relatively small dove-sized jackdaws to the Common Raven of the Holarctic region and Thick-billed Raven of the highlands of Ethiopia, the 40 or so members of this genus occur on all temperate continents and several offsh...
s, then we would describe the set of crows that is of interest. Notice that if we choose a population like all crows, we will be limited to observing crows that exist now or will exist in the future. Probably, geography
Geography

Geography is the study of the Earth and its lands, features, inhabitants, and phenomena. A literal translation would be "to describe or write about the Earth"....
 will also constitute a limitation in that our resources for studying crows are also limited.

Population is also used to refer to a set of potential measurement
Measurement

Measurement is the process of assigning a number to an attribute according to a rule or set of rules. The term can also be used to refer to the result obtained after performing the process....
s or values, including not only cases actually observed but those that are potentially observable
Observable

In physics, particularly in quantum physics, a system observable is a property of the State that can be determined by some sequence of physical operational definition....
. Suppose, for example, we are interested in the set of all adult crows now alive in the county of Cambridgeshire
Cambridgeshire

Cambridgeshire is a Counties_of_the_United_Kingdom#England in England, bordering Lincolnshire to the north, Norfolk to the northeast, Suffolk to the east, Essex, England and Hertfordshire to the south, and Bedfordshire and Northamptonshire to the west....
, and we want to know the mean weight of these birds. For each bird in the population of crows there is a weight, and the set of these weights is called the population of weights.

Subpopulation

A subset
Subset

In mathematics, especially in set theory, a Set A is a subset of a set B if A is "contained" inside B. Notice that A and B may coincide....
 of a population is called a subpopulation. If different subpopulations have different properties, they can often be better understood if they are first separated into distinct subpopulations.

For instance, a particular medicine may have different effects on different subpopulations, and its effects may be obscured or dismissed if the subpopulation is not identified and examined in isolation.

Similarly, one can often estimate parameters more accurately if one separates out subpopulations: distribution of heights among people is better modeled by considering men and women as separate subpopulations, for instance.

Populations consisting of subpopulations can be modeled by mixture model
Mixture model

In mathematics, the term mixture model is a model in which independent variables are fractions of a total....
s, which combine the distributions within subpopulations into an overall population distribution.

See also

  • Population
    Population

    File:Population density.pngIn biology, a population is the collection of inter-breeding organisms of a particular species; in sociology, a collection of human beings....
  • Sample (statistics)
    Sample (statistics)

    In statistics, a sample is a subset of a Statistical population. Typically, the population is very large, making a census or a complete enumeration of all the values in the population impractical or impossible....
  • Sampling (statistics)
    Sampling (statistics)

    Sampling is that part of statistical practice concerned with the selection of individual observations intended to yield some knowledge about a population of concern, especially for the purposes of statistical inference....
  • Statistics
    Statistics

    Statistics is a Mathematics pertaining to the collection, analysis, interpretation or explanation, and presentation of data. It also provides tools for prediction and forecasting based on data....


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