SOCI. 104

SOCI. 104 Levels of measurement

THREE LEVELS OF MEASUREMENT

Some variables distinguish one category from another, while other variables are representing an exact numerical quantity. Being able to distinguish between the three levels of measurement is important. The three levels of measurement we will use in this class are interval-ratio, ordinal and nominal.

INTERVAL-RATIO VARIABLES

Ordered groups where the intervals between the values are equally spaced. All cases expressed in same, meaningful and measurable units, i.e quantifiable. Percentages are typically interval-ratio.

Examples: Number of children a person has, budget of a university, a worker’s annual income.

ORDINAL VARIABLES

Ordered groups where the scales do not specify “distance” between categories

Example: Department rankings, likert scale questions on a survey

Example of Likert Scale responses

NOMINAL VARIABLES

Groups that cannot be ordered, nor ranked or a dichotomous categorization

Examples: gender, racial status, ethnicity, religion, geographical location, political affiliation, such as Democrat, Republican, Green Party, or Independent.

Importantly, interval-ratio variables can be made into ordinal level variables and also nominal level variables. Ordinal level variables can be made into nominal level variables. Nominal level variables cannot be made into ordinal-level nor interval-ratio level variables.

It is important that you are able to create survey questions that can provoke answers at all levels of measurement for some variables. For example, age or income. What survey questions could we ask that would get a. an interval-ratio level variable response, b. an ordinal level variable response and a nominal level response?

"How old are you?"

"Do you consider yourself young, middle-aged or elderly?"

"Are you 21 years old or over?"

"How old are you?" prompts people to respond with interval-ratio level answers.

"Do you consider yourself young, middle-aged or elderly?" prompts people to respond with ordinal level answers.

"Are you 21 years old or over?" prompts people to respond with nominal level answers.

Created By

Megan Thiele

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