Statistics Definitions and Terminology

In statistics, an entire group of people or things is called a population or universe. A population can be infinite or finite. Examples of finite populations include the number of airplanes owned by an airline, or the potential consumers in a target market. Examples of infinite populations include the number of products manufactured by a company that plans to be in business forever, or the growth of bacteria given ample resources to grow.

A small part of the entire group chosen for study is called a sample. For example, in a study of the heights of students at a particular college, the entire student body is the population. The population is finite because it’s not growing in any way as the study is conducted. Instead of studying every student in the population, we may choose to work with a sample of only 100 students.

Frequency Distributions

Data that has not been organized in any way is called raw data. Data that has been sorted into ascending or descending order are called an array. The range of the data is the difference between the largest and the smallest number in that array.

Question:   Arrange the following in ascending order; find its range.

56.2,   72.8,   58.3,   56.9,   67.5


Largest value: 72.8

Smallest value: 56.2

Range: 72.8 – 56.2 = 16.6

Ascending order means smallest to largest: 56.2 → 56.9 → 58.3 → 67.5 → 72.8