Main distinctions: Numbers as numbers vs. as ranks vs. as (categorical) labels.
Example: How tall are people?
The same measurement can be made (mapped, represented) on different scales:
size in cm: comparisons between values are scaled (e.g., 20% larger, etc.)
rank within group: comparisons between people are possible, but no longer scaled
categories: can be ordered (small-medium-tall) or unordered (fits vs. does not fit)
- They allow different types of calculations and tests.
- They should be assigned to different data types.