ABSTRACT
There are four types of measurement scales: nominal, ordinal, interval, and ratio (Stevens 1946). The nominal scales are based on qualitative data such as a name or label. The ordinal scales use rank order but don’t indicate the degree of difference. Examples of ordinal scales include OK or not OK, good or bad. The interval scales give a degree of difference, but not a ratio between the differences. For example, 18°C is not twice as hot as 9°C. The ratio scales can be ordered to show the magnitude of the difference between values and the intervals between values are equal. For example, 18 cm is twice as long as 9 cm. Examples of scales are shown in Table 10.1.
