Dyr og Data
Statistical thinking — types of data
Wednesday, 19 August 2026
Random variables
A random variable is a variable whose values are not known for certain before a sample is taken
Discrete
- Take only a finite set of values
- Does an animal have a disease?
- Number of treatments with antibiotics
- Sex
Continuous
- Take any value
- Penguin flipper length
- Milk yield of a cow at a milking
Measurement level
A further classification of random variables relates to the scale on which we measure them. Some discrete variables can be nominal or ordinal
- A nominal scale is for unordered categories
- Species
- Sex
- Religion
- An ordinal scale is where there is some implicit ordering to the categories
- Pain on a scale from 1–10
- Behaviour
Measurement level
Continuous variables can be interval or ratio scaled. Discrete counts can also be considered ratio scaled variables.
- Interval scaled variables are those with equal intervals along the scale
- Temperature (˚C)
- As no fixed zero value, ratios can not be calculated
- 5˚C is not half the temperature of 10˚C
- Ratio scaled variables
- Have a defined 0 point
- Temperature (K)
Gavin Simpson | Department of Animal & Veterinary Sciences