Nominal
- Purpose is to name, label or classify
- Cannot do anythingelse to numbers except count
- Categories might be useful, but numbers are essentially irrelevant, could be misleading
Ordinal
- Put individuals in order (rank) – “moreness”
-Distance between each number is unknown
- Cannot add/subtract, etc.
- But numbers themselves do represent meaning (for each individual)
Interval
- Specific unit of measurement, with equal distances
- Know rank order, plus can add/subtract
-So can do linear transformations, compare
Ratio
- Exact zero point, true absence of characteristics
- Can do all mathematical operations
- Very unlikely in psychology – e.g., EEG, response time | 
