quirkyresearcher

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What is a Dichotomous Variable?

Dichotomous variables are nominal (also known as categorical) variables that have only two categories. 

Example:

A question that allows the respondent to provide a “yes” or “no”, i.e. do you have a car?

Gender can be a dichotomous variable if respondents are only able to provide “male” or “female” as their answer. However, you should think whether or not to provide more than two options for this answer, i.e “male”, “female”, “transgender”. This would not be a dichotomous variable. 

[quirkyresearcher]

What is an Ordinal Variable?

Ordinal variables are very similar to nominal (categorical) variables in the sense that they have two or more categories. The key difference is that they are concerned with the ordering / ranking of categories within the variable. It is important to remember that although ordinal variable can be put into an order / ranked, they cannot have a value put on them. In other words, one of the categories within an ordinal variable cannot be said to be more valuable than another (confused? See example below).

Example of an Ordinal Variable:

To understand what an ordinal variable is, here is a fictitious (fake) example of a research survey question about understanding variables. 

Question: 

How stressed are you about understanding ordinal variables?

Possible answers:

1) Very stressed [most stressed]

2) Not too stressed [middle stressed]

3) Not all stressed [least stressed]

Point:

This is an ordinal variable because within the variable there are three categories to choose from (very stressed, not too stressed, not at all stressed). The responses are ranked from most stressed (1), middle (2), and least stressed (3). However, you cannot say that option 1 is twice as stressed as option 3. Get it?

[quirkyresearcher]

What is a Nominal / Categorical Variable?

A nominal variable (also known as a categorical variable) is one that has two or more categories within it. Nominal variables cannot be put into, or allocated, any order, i.e. low to high values. Nor can they be quantified, i.e. carry out a mathematical function upon (add, subtract, multiply, etc.). 

Examples of Nominal Variables:

Gender (male, female, etc.)

Marital status (single, married, divorced, etc.)

Hair colour (brown, blonde, etc.)

Eye colour (blue, green, etc.)