The Use of Samples:
4.1 POPULATION AND SAMPLEThe objective of any scientific inquiry is to make measurements and to
establish relationships that hold for a broad class of objects. The physicist
attempts to derive a law for the period of pendulums, applicable to all
pendulums of a certain description. The botanist attempts to find the
relationship between plant hormone and growth in a wide class of plants.
The economist hopes to find a relationship between family income and
consumption that will hold among all families of a given description. The
broad class of objects to which the measurement or relationship is
applicable will be called the population or the universe.
4.1.1 The Need for SamplesOne way to be sure that a measurement applies to an entire population
is to examine every item in the population. Unfortunately, this is often
impossible for several reasons:
|1. ||Much of the population may not yet exist. For example, under.
standing the effect of plant hormone on growth leads to improvement in
the yield of crops as yet unplanted. Knowledge of the properties of a
drug will help to cure people not yet ill and, for that matter, still unborn.|
|2. ||Exploration of the relationship may be destructive. A piece of
cable whose strength has been tested by breaking it under measured
conditions cannot be used again.|
|3. ||Finally, we generally have neither the time nor the resources to
examine the entire population, even where physically possible to do so.|
Questia, a part of Gale, Cengage Learning. www.questia.com
Book title: Statistics:An Introduction to Quantitative Economic Research.
Contributors: Daniel B. Suits - Author.
Publisher: Rand McNally.
Place of publication: Chicago.
Publication year: 1963.
Page number: 54.
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