What are the levels of measurement in nursing research?

Nominal scale: The lowest level of measurement, nominal scales categorize data into different groups or categories. There is no order or hierarchy to these categories, and the numbers assigned to them are simply labels. For example, you might use a nominal scale to categorize patients by gender (male, female) or by diagnosis (heart failure, stroke, diabetes).

Ordinal scale: Ordinal scales rank data in order, from lowest to highest. The intervals between the ranks are not necessarily equal, however. For example, you might use an ordinal scale to rate patients' pain levels on a scale of 0 to 10, where 0 means no pain and 10 means the worst pain imaginable.

Interval scale: Interval scales have both order and equal intervals between the ranks. This means that you can not only rank the data, but you can also calculate the difference between two data points. For example, you might use an interval scale to measure patients' blood pressure in millimeters of mercury (mmHg).

Ratio scale: The highest level of measurement, ratio scales have all of the properties of interval scales, plus they have a true zero point. This means that you can not only rank the data and calculate the difference between two data points, but you can also say that one data point is twice as big as another data point. For example, you might use a ratio scale to measure patients' weights in kilograms (kg).

The level of measurement you use in your nursing research will depend on the type of data you are collecting and the analyses you plan to conduct. Nominal and ordinal scales are appropriate for descriptive statistics, while interval and ratio scales are required for inferential statistics.