Levels of Measurement_C207

Levels of Measurement

• There are 4 levels of measurement: nominal, ordinal, interval, and ratio.

• Use the acronym n o I r (the French word for black) to remember these levels.

• Nominal and ordinal data are categorized; they are not numbers.

Nominal Data

• Nominal data represents categories without a logical sequence.

  • Example: Types of rental cars (economy, compact, intermediate)

  • Cannot be ranked or ordered logically.

• Example of nominal: Colors of cars (red, yellow, blue) - no logical sequence exists.

Ordinal Data

• Ordinal data consists of categories that have a logical sequence or order.

  • Example: Rental cars ranked from smallest to largest or by luxury level.

  • You can order them, but the distance between categories is not defined.

Numerical Data - Interval vs. Ratio

• Interval and ratio are numerical data, distinguished by the meaning of zero.

Interval Data

• Zero acts as a placeholder.

  • Example: Temperature (0 degrees does not indicate no temperature).

  • You can have negative values (e.g., -2 degrees).

Ratio Data

• Zero indicates an absence of quantity.

  • Example: Miles a car can travel at a given temperature.

  • If 0 miles is possible due to certain conditions, it reflects true absence.

• Also applicable to:

  • Price - if the price is $0, it means no cost.

Practical Applications

• When encountering data, ask:

  • Is it nominal? (categories, no order)

  • Is it ordinal? (categories, with order)

  • Is it interval? (numbers, zero as a placeholder)

  • Is it ratio? (numbers, zero as absence)

• When unsure, consult an instructor for clarification.