c. What is required.

The principles of statistics outline ways in

which samples may be taken, how large a sampling is required, and the type

of averages that are appropriate to particular situations. All these items

will be discussed in due time.

First, however, examine some pertinent

definitions.

d. Definitions.

(1) Population.

The total things, events, or quantities under

consideration. The size and extent of the population should be described.

EXAMPLE. All

the workshoes in Kansas or all the golf clubs sold in Oregon.

Each item of

the population as a whole has characteristics (for example,

length). The

population as a whole has characteristics of characteristics

(for example,

the average length).

(2) Parameter. Some characteristic of the population. Generally, a

parameter is some truth about the population that we are trying to discover

(as accurately as possible) by means of sampling and statistical

manipulation.

(3) Sample. A group drawn from the population. Obviously, we cannot

examine all the workshoes in Kansas, but if we would select a random sample,

of 10 shoes from each county, the average length of the sample would be a

good guess as to the average length of all the shoes. To avoid confusion,

sometimes the group is called a sampling, and each unit of it is referred to

as a sample.

(4) Statistic. Some calculated value derived from a sampling. This

is an estimate of some corresponding value pertaining to the population.

How good an estimate it is depends on the nature and size of the population,

the way in which the sampling was taken, and the statistics computed.

(5) Data. A group of facts or statistics; often used with a singular

verb. This word is the plural of datum, which in a statistical sense means

a particular value or fact.

(6) Observation.

In a scientific sense, this is considered to be the

gathering of data.

e. Observation.

(1) This is the source of practically all objective data. Usually,

it is obtained with the aid of some measuring device. There is very little

subjectivity connected with the reading of the device, since, when it is

used properly, different people will get the same readings under the same

set of conditions.

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