Levels of Measurement

Nominal Level of Measurement

  • Etymology: The term "nominal" is derived from the adjective form of the word "NAME."
  • Definition: The nominal level of measurement is used to identify names, categories, or labels.
  • Data Type: This is classified as qualitative type data, consisting of words or phrases rather than numerical values.
  • Examples:
    • Eye color
    • Hair color
    • Gender
    • Ethnicity
    • Binary responses (e.g., Yes/No)
    • Religious preference
    • Political affiliation

Ordinal Level of Measurement

  • Etymology: The term "ordinal" is derived from the adjective form of the word "ORDER."
  • Definition: This level consists of categories that possess a distinct sense of order.
  • Data Type: Like the nominal level, this involves qualitative type data.
  • Subjectivity: The ranking used at this level is sometimes based on the specific interpretation of the researcher.
  • Examples:
    • Academic Degrees: Types of college degrees such as Associate, Bachelors, Masters, and Doctorate.
    • Contest Placements: Standings in judging contests like pie cook-offs, chili cook-offs, or art drawing competitions (e.g., 1st1^{st} place, 2nd2^{nd} place, 3rd3^{rd} place).
    • Ratings: Movie Ratings, including G, PG-13, PG, R, and X.
    • Evaluations: Letter Grades such as A, B, C, D, and F.

Interval Level of Measurement

  • Definition: The interval level involves quantitative data that incorporates a sense of ranking or order.
  • Mathematical Properties: At this level, it is possible to calculate the difference between ranks using addition or subtraction.
  • The Concept of Zero: There is no "true" zero at the interval level.
    • Zero functions strictly as a placeholder.
    • A value of zero does not imply the state of "none" or "nothing."
  • Examples:
    • Temperature: A temperature measurement of 0∘0^{\circ} does not signify the total absence of temperature; rather, it indicates a specific state of being cold.
    • Standardized Testing: This includes IQ Scores, SAT Scores, and ACT Scores. A score of 00 on these tests does not indicate a lack of intelligence, an absence of knowledge, or the absence of a brain; it merely suggests the individual does not perform well on the specific test format.

Ratio Level of Measurement

  • Definition: The ratio level involves quantitative data that maintains a sense of ranking or order.
  • Mathematical Properties: Data at this level allows for the full range of arithmetic operations, including addition, subtraction, multiplication, and division.
  • The Concept of Zero: Unlike the interval level, the ratio level possesses a "true" zero.
    • At this level, a value of zero explicitly signifies "none" or "nothing."
  • Examples:
    • Salary: A salary of 00 indicates that a person is working for free or for nothing.
    • Duration: A measurement of 00 minutes signifies that no time remains, or there is "none."
    • Physical Dimensions: Measurements such as Height and Weight.