Examples of variables on interval scale (besides temperature) Besides temperature, what are some examples of variables on interval scale?
Examples from economics and/or finance would be appreciated.
 A: I will consider a variable on an interval scale to be  one which has an order of their elements, with a meaningful and comparable difference, but with a zero which is not meaningful. This is in contrast with ratio scales which have all the qualities of interval scales and also a meaningful zero, where zero means the quantity vanish, does not exist.
Now some examples:

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*temperature: if measured in kelvin is on a ratio scale, since 0 K means there is no heat; when temperature is measured in Celsius or Fahrenheit is on an interval scale

*dates: interval scale, since you have no zero; you can choose your reference how do you like, it has no meaning

*location in Cartesian space: you can choose your origin however you like, having a point on $0$ on the real axis in 1D space, does not mean it does not have a location; note however that distance from an origin is a ratio scale measurement

*cardinal direction measured in degrees from true North is on interval scale; the departure from North, in contrast, is on ratio scale

*custom scores - for example a score between 1 and 5 which defines satisfaction; while there is some debate if this scores are ordinal or not, there are many which considers them interval scales, even in sociology texts

*IQ scores, GPA and similar - most of them are calibrated around some mean, but no human is assumed to have a 0 score, equivalent of no intelligence at all (even if I can think that some of them have good chances to break that)

A: In economics, utility  can be considered to be on interval scale. There is some disagreement whether utility should be ordinal or cardinal, but in the case of cardinal utility, it is measured on the interval scale.
The following is a quote from Wikipedia's article on Cardinal utility, section Measurability:

It is helpful to consider the same problem as it appears in the construction of scales of measurement in the natural sciences. In the case of temperature there are two degrees of freedom for its measurement - the choice of unit and the zero. Different temperature scales map its intensity in different ways. In the celsius scale the zero is chosen to be the point where water freezes, and likewise, in cardinal utility theory one would be tempted to think that the choice of zero would correspond to a good or service that brings exactly $0$ utils. However this is not necessarily true. The mathematical index remains cardinal, even if the zero gets moved arbitrarily to another point, or if the choice of scale is changed, or if both the scale and the zero are changed. Every measurable entity maps into a cardinal function but not every cardinal function is the result of the mapping of a measurable entity. The point of this example was used to prove that (as with temperature) it is still possible to predict something about the combination of two values of some utility function, even if the utils get transformed into entirely different numbers, as long as it remains a linear transformation.

See also Wakker "Explaining the characteristics of the power (CRRA) utility family" (2008).
