Definitions

Measurement - the assignment of numbers or codes according to prior-set rules.

Variable - a measurement that can be expressed as more than one value in a study; the generic "thing" being measured (e.g., AGE, SEX, etc.) (Remark: Not all variables are random, although random variables are variables that varies randomly either according to its method of selection or through some other source of variation.)

Value - a realization measurement; a data point. (e.g., 31, "male").

Population - the universe of all potential values. Populations may be either real and finite or hypothetical and infinite. The larger group to which inference will eventually be made.

Sample - a subset of the population.

Simple random sample - a sample in which each member of the population has an equal (non-zero) probability of selection into the sample. A simple random sample is the most basic type of probability sample. A probability sample is a sample in which each member has known probability of entering the sample.

Empiricims - based on observation (from the Greek empirikos - experience; compare to rationalism, which is based purely on reason for the purpose of establishment of truth.)