Variable

n    A concept which can take on different quantitative or qualitative values

Ex: weight, height, income, etc

n    Variable is a ‘symbol to which values or numerals are assigned’.

Variable – Construct /Quality / Property to be studied

Types of Variable

n    Independent Variable

n    Dependent Variable

n    Extraneous Variable

n    Continuous Variable

n    Discrete Variable

n    Ordinal Variable

n    Nominal variable

Independent Variable

n    The variable that is antecedent to the dependent variable is a ‘independent variable’

n     The variable whose change results in the change in another variable is called an independent variable.

n    An independent variable is the one that influences the dependant variable in either a positive or negative way

Dependent Variable

n    The variable which depends upon or is a consequence of another variable is a ‘dependent variable’

n    The variable that changes in relationship to changes in another variable(s) is called dependant variable.

Defining Independent  & Dependent Variable

n     Independent V                   Dependent V

Presumed Cause                                   Presumed Effect

Stimulus                                                Response

Predicted From…                                Predicted To…

Antecedent                                           Consequence

Manipulated                             Measured Outcome

Input                                                    Output

Treatment                                             Outcome

Extraneous Variable

n    Independent variable that are not related to the purpose of the study but may affect the dependent variable are termed as an ‘extraneous variable’

  IV                                                                  DV

                                   

                                    EV

Continuous Variable

n     Phenomena which can take on quantitatively different values even in decimal points are called as a ‘continuous variable’

Ex: Age

n     height in centimetres (2.5 cm or 2.546 cm or 2.543216 cm)

n     temperature in degrees Celsius (37.20C or 37.199990C etc.)

Discrete Variable

n    If the values can only be expressed in integer values, they are non-continuous variable or discrete variable

Ex: number of children

n    number of visits to a clinic (0, 1, 2, 3, 4, etc).

n    number of friends (0, 1, 2, 3, 4, 5, etc.)

Ordinal variables

n    These are grouped variables that are ordered or ranked in increasing or decreasing order.

For example:
High income (above $300 per month);
Middle income ($100-$300 per month); Low income (less than $100 per month).

Other examples are:

n    Agreement with a statement: fully agree, partially agree, fully disagree

n    Disability: no disability, partial disability, serious or total disability

n    Seriousness of a disease: severe, moderate, mild

Nominal variables

n    The groups in these variables do not have an order or ranking in them.

For example: 

Sex: male, female

Main food crops: maize, millet, rice, etc.

Religion: Christian, Muslim, Hindu, etc.

Factors rephrased as variables