Certified Rehabilitation Counselor Practice

Which scale would be used to evaluate a person's weight?

1. Ordinal scale

2. Nominal scale

3. Ratio scale

4. Interval scale

The correct answer is: Ratio scale

The correct answer is the ratio scale, which is specifically designed to measure quantitative data in a way that allows for the full range of statistical analyses. A ratio scale possesses all the characteristics of an interval scale, including equal distances between values, but also provides a meaningful zero point, which indicates the absence of the quantity being measured. In the case of evaluating a person's weight, the scale not only allows for the comparison of differences in weight (e.g., 160 pounds is heavier than 150 pounds) but also conveys a true zero point, where a weight of zero corresponds to the absence of weight. This means that one can say that someone weighing 200 pounds is twice as heavy as someone weighing 100 pounds, which is a crucial property of ratio scales. Understanding why other scales do not apply helps to clarify the unique attributes of the ratio scale. An ordinal scale ranks data but does not measure the precise differences between them, while a nominal scale categorizes without any quantitative analysis. The interval scale, while it does reflect equal distances between values, lacks a true zero point, which makes it unsuitable for measuring weight.