Levels of Measurement
Measurement scales differ in their level of measurement. There
are four common levels of measurement:
- Nominal scales are only labels.
- Ordinal Scales are ordered but are not
truly quantitative. Equal intervals on the ordinal scale do not imply equal
intervals on the underlying trait.
- Interval scales are are ordered and equal
intervals equal intervals on the underlying trait. However, interval scales
do not have a true zero point.
- Ratio scales are interval scales that do
have a true zero point. With ratio scales, it is sensible to talk about one
value being twice as large as another, for example.