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