Four levels of measurement scales include the nominal scale, the ordinal scale, the interval scale and the ratio scale.
Nominal scale
Nominal measurement is the process of classifying different objects into categories based upon some defined characteristics. Examples are sex, color of hair/eyes, ethnic background, makes of car and so on. The properties of nominal data are as follows:
1. data categories are mutually exclusive (an object can belong to only one category).
2. data categories have no logical order.
In summary, a nominal scale simply classifies without order.
Ordinal scale
with the ordinal scale, one additional property is present over those of the nominal scale--a logical ordering of the categories. The variable measured is such that differences in the amount of the characteristics possessed is discernible.
Examples are:
- course grade: A, B+, B, C+ C, D and F
- level of satisfaction: low, medium and high
The properties of ordinal data are as follows:
1. data categories are mutually exclusive
2. data categories have some logical order
3. data categories are scaled according to the amount of the particular characteristics they possess
