Scales of Measurement What is a nominal scale? A scale that categorizes items

What is an ordinal scale?

A scale that categorizes and rank orders items

What is an interval scale?

A scale that categorizes and rank orders items, and has equal intervals

What is a ratio scale?

A scale that categorizes and rank orders items, has equal intervals, and a zero that means the absence or none of the thing being measured

Types of Variables

• Discrete Variables:– consists of separate categories

• Continuous Variables:– Variable that is not measured on distinct

categories

Real Limits

• A score on a continuous variables could fall anywhere on the scale, even between units– On a continuous scale of 1 to 5, it is possible to obtain a

2.5

• Real Limits are used to account for this possibility– They define boundaries at +/- half of a unit of the scale– If a scale is in units of 1, then the real limit is +/- 0.5 for

each score