When would you use a ratio scale in research?

Using a ratio scale in research is particularly relevant when precise mathematical operations are necessary. A ratio scale not only allows researchers to establish an order among data points but also enables them to perform a variety of mathematical operations, such as addition, subtraction, multiplication, and division. This is because a ratio scale has a true zero point, which signifies the absence of the quantity being measured. This property allows for meaningful comparisons and calculations, such as calculating ratios and proportions, which are essential when analyzing data in many fields, including psychology.

For instance, in measuring height or weight, a ratio scale provides the ability to say that one person is twice as heavy as another. Such comparisons are not possible with nominal or ordinal scales, where the concepts of zero and ratio comparisons do not hold. Therefore, using a ratio scale is fundamentally about ensuring that the data can support more complex statistical analyses that require precise measurement and can incorporate a wide range of mathematical computations.