Basic Terms

Element or member

An element or member of a sample or population is a specific subject or object (for example, a person, firm, item, state or country) about which the information is collected.

Variable

A variable is a characteristic under study that assumes different values for different elements. Data can either be univariate, bivariate or multivariate depending on the number of variables. In contrast to a variable, the value of a constant is fixed.

Observation or measurement

The value of a variable for an element is called an observation or measurement.

Data set

A data set is a collection of observations on one or more variables.

Example 1.1

The table below gives information on 1992 profits (in millions of U.S dollars) of six international companies.  We can call this group of companies a sample of six companies. Each company listed in this table is called an element or a member of the sample.  Elements are also called observational units.

Table 1.1: Profits of Six International Companies

Company	1992 Profits (millions of dollars)
Exxon, United States	4800
Toyota Motor, Japan	2222
Daimer – Benz Germany	891
Guinnes, Britain	814
Northern Telecom, Canada	548
Fiat Group, Italy	375

• The 1992 profits of companies in this example is called a variable.
• Each of the values representing the 1992 profits of six companies in Table 1.1 is called an observation or measurement.
• The information given in the table 1.1 on 1992 profits of companies is called the data or a data set.