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 CensusAtSchool Australia

CaSQ 3C - Categorical Data: What’s the Difference Between Nominal and Ordinal?

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 Data Data can be classified into two different types. Categorical Values or observations that can be sorted into groups or categories. Bar charts and pie graphs are used to graph categorical data. Numerical Values or observations that can be measured. And these numbers can be placed in ascending or descending order. Scatter plots and line graphs are used to graph numerical data. Nominal Values or observations can be assigned a code in the form of a number where the numbers are simply labels. You can count but not order or measure nominal data. Examples: Sex, and eye colour. Ordinal Values or observations can be ranked (put in order) or have a rating scale attached. You can count and order, but not measure, ordinal data. Example: house numbers and swimming level. Discrete Values or observations can be counted (1,2,3,....) and are distinct and separate,. Examples: the number of kittens in a litter; number of threads in a sheet, number of bricks in a wall. Continuous You can measure continuous data. Values or observations may take on any value within a finite or infinite interval. Examples: height, time and temperature.

1. Sort the following CensusAtSchool question topics according to whether they will yield ordinal or nominal data.

 Birthdate Favourite sport/activity Favourite type of music How internet is accessed at home How internet is used at home School postcode Travel method to school Year level

 Nominal 1. 2. 3. 4. 5. Ordinal 1. 2. 3. 4. 5.

2. Why is ‘State/Territory or Country that you were born in’ considered to be nominal data?

3. We know that postcode is categorical data, decide whether you think it is nominal or ordinal data, and justify your reasoning.