Some Basic Definitions in Statistics

Constant

A quantity which can assume only one value is called a constant. It is usually denoted by the first letters of the alphabet, a,b,c.
For example: The value of \pi = \frac{{22}}{7} = 3.14159... and the value of e = 2.71828....

Variable

A quantity which can vary from one individual or object to another is called a variable. It is usually denoted by the last letters of the alphabet, x,y,z.

For example: Heights and weights of students, income, temperature, number of children in a family, etc.

Continuous Variable

A variable which can assume each and every value within a given range is called a continuous variable. It can occur in decimals.

For example: Heights and weights of students, speed of a bus, the age of a shopkeeper, the life time of a T.V, etc.

Continuous Data

Data which can be described by a continuous variable are called continuous data.
For example: Weights of 50 students in a class.

Discrete Variable

A variable which can assume only some specific values within a given range is called a discrete variable. It cannot occur in decimals; it can only occur in whole numbers.
For example: Number of students in a class, number of flowers on a tree, number of houses on a street, number of chairs in a room, etc.

Discrete Data

Data which can be described by a discrete variable are called discrete data.
For example: Number of students in a college.

Quantitative Variable

A characteristic which varies only in magnitude from one individual to another is called a quantitative variable. It can be measurable.
For example: Wages, prices, heights, weights, etc.

Qualitative Variable

A characteristic which varies only in quality from one individual to another is called a qualitative variable. It cannot be measured.
For example: Beauty, marital status, rich, poor, scent, etc.