- A variable whose values are ordered, that can be multiplied by a scalar, and for which the magnitude of differences in values is meaningful.
- 1992, Jack Hirshleifer; John G. Riley, The analytics of uncertainty and information, page 14:
- In dealing with certainty choices, standard economic theory treats utility (intensity of preference) as an ordinal rather than a cardinal variable.
- 2001, Bruno S. Frey; Alois Stutzer, Happiness and economics: how the economy and institutions affect well-being, page 185:
- The least squares estimation treats happiness as a cardinal variable.
- 2007, Ian Gough; J. Allister McGregor, Wellbeing in developing countries: from theory to research, page 266:
- Life Satisfaction was handled as a cardinal variable, with values between one and seven, where one was assigned to the lowest level of satisfaction