WHAT ARE LEVELS OF MEASUREMENT?

September 22, 2025

Understanding the levels of measurement helps you apply suitable statistical methods and make more accurate and meaningful interpretations of data. Data can be classified into four levels of measurement—nominal, ordinal, interval, and ratio.

They provide different levels of detail. Each one of the four levels increasingly gives more possibilities for examining your data in detail.

Measures that produce meaningful results

Measure	Mode	Median	Mean
Nominal	✓
Ordinal	✓	✓
Interval	✓	✓
Ratio	✓	✓	✓

Numbers or words may represent the values of the nominal variables, but the numbers are merely labels. A sum obtained by adding the numbers together is not meaningful. You cannot put nominal data into any order.

Ordinal variables' values are different from nominal variables’ values. Unlike nominal variables’ values, ordinal values can be ordered according to some statistical characteristic.

Intervals can accept negative values. However, 0 (zero) denotes the presence of a value. Temperature does not start from zero. Consequently, for instance, 20°C is not twice as hot as 10°C, and ratios (20 / 10) and (10 / 20) are not meaningful.

Ratio variables’ minimum value is zero. And 0 does represent the absence of a value; for example, the number of insurance claims received in a day could be zero, one, or more. Ratio measure allows meaningful ratio comparisons that aren’t possible with lower-level measurements. For example, the monthly income figures of five youths are $100, $50, $300, $120, and $140. The lowest income is $50. The figures can be ordered ($50, $100, $120, $140, and $300). The difference between the two figures ($140 - $120 = $20) and ratios ($100 / $50) is meaningful.

SPSS Measures

Measures available in SPSS can be used for nominal, ordinal, interval, and ratio data. However, SPSS does not differentiate between interval and ratio data. Either Interval or ratio data can use the “Scale” measure in SPSS.

Summary of the measures

Characteristic	Nominal	Ordinal	Interval	Ratio
Qualitative	✓	✓
Quantitative			✓	✓
True zero value				✓
Order		✓	✓	✓
Math operation	Count	Order	±	±,÷,×
Quantify difference			✓	✓