Ordinal If the data have a meaningful order or rank then the variable is ordinal. Let’s consider a few examples (see Figure 1): Responses to a likert scale question on a questionnaire. The responses (strongly disagree, disagree, neutral, agree, strongly agree) have a meaningful order to them. Grouped income. This is not the exact income, but an income bracket (£0-£5000, £5001£10000, £10001-15000, etc…). These groupings have a meaningful order (i.e., £0-£5000 is less than £5001-£10000, etc…). Olympic medal. Say we had a list of every member of the GB team that earned a medal at the 2012 Olympics. The medal they each received (gold, silver and bronze) has a meaningful rank because gold represents 1st place, silver 2nd and bronze 3rd. Nominal If the data do not have a meaningful order or rank then the variable is nominal. Let’s consider a few examples (see Figure 1): Marital status. The possible responses (single, married, divorced, widowed, etc…) cannot be ordered or ranked in a meaningful way. That is, I can’t say that single is better than married, married is better than divorced and divorced is better than widowed. Likewise, although I can say that married comes after single, we cannot arrange divorced and widowed in a meaningful order as one does not follow the other. Gender. The typical responses of Male and Female do not have a meaningful rank or order as we cannot say that one is better than the other (regardless of your personal opinion).
Variables Categorical
Quantitative
Nominal
Ordinal
Scale
(unranked categories)
(ranked categories)
(not grouped)
Marital status Political party Eye colour Gender
Likert scale Grouped income Olympic medal
Height Weight Score on a test Duration (time)
Figure 1. Levels of measurement
Created by ASK (2012)
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