Levels of Measurement

Nominal level(scaled):

Data that can only be classified into categories and cannot be arranged in an ordering scheme.

Examples: eye colour, gender, religious affiliation

Mutually exclusive: 

An individual or item that by virtue of being included in one category must be excluded from any other category.

Example: eye colour

Exhaustive:

Each person, object, or item must be classified in at least one category.

Example: religious affiliation

Ordinal level:

involves data that may be arranged in some order, but differences between data valuses cannot be determined or are meaning less.

Example: During a taste test of 4 colas, cola C was ranked number 1, cola B was ranked number 2, cola A was ranked number 3, and cola D was ranked number 4.

Interval level:

Similar to the ordinal level with the additional property that meaningful amounts of differences between data values can be determined. There is no natural zero point.

Example: Temperature on the Fahrenheit scale

Ratio level:

The interval level with an inherent zero starting point. Differences and ratios are meaningful for this level of measurement.

Examples: money, height of NBA player