Why does the scale of measurement matter?
The scale of measurement of our variables determines the mathematical operations that are permitted for those variables. In turn, these mathematical operations determine which statistics can be applied to the data.

The chart below lists the scales of measurement that we have reviewed in this exercise and the types of statistics that can be applied to variables created using these scales of measurement.

Keep in mind that many psychologists make no distinction between approximately interval, interval, and ratio data. This is a matter of preference rather than being “right” or “wrong.” Check with your instructor about this matter.