What is a primary feature of ratio level measures?

A primary feature of ratio level measures is that they possess a fixed unit and an absolute zero point. This means that not only do the values at this level allow for the full range of mathematical operations—such as addition, subtraction, multiplication, and division—but they also enable meaningful comparisons between the data points. For instance, if one measurement is twice the value of another, this is inherently significant due to the existence of an absolute zero that represents a complete absence of the quantity being measured.

This differs from other scales, such as nominal or ordinal scales, which either do not use numbers for categorization or do not provide consistent measures across the scale. In the case of interval level measures, while they can show differences and allow for ranking, they lack a true zero point, which would limit the interpretation of ratios. The fixed unit ensures consistency and reliability in measurements, making ratio measures essential in fields such as criminal justice research, where precise quantification of data is necessary for analysis and interpretation.