American Institute of Certified Planners (AICP) Practice Exam

Which of the following describes a Ratio Scale?

1. Ordered relationships with arbitrary equal intervals

2. Categorization without any numeric representation

3. Ordered relations with defined intervals and an absolute zero

4. Measurable aspects of unique characteristics

The correct answer is: Ordered relations with defined intervals and an absolute zero

A ratio scale is characterized by ordered relationships that include defined intervals and an absolute zero point. This type of scale allows for the comparison of both differences and ratios between measurements. For example, in a ratio scale, the zero point indicates a complete absence of the quantity being measured, which means that one can meaningfully say that one measurement is twice or half as much as another. This is contrasted with other types of scales. For instance, an interval scale lacks an absolute zero; it can measure the difference between values but not the ratios (e.g., temperature in Celsius). Ordered relationships with arbitrary equal intervals denote a system that may not have a true zero, but has consistent units of measurement, which is not sufficient to describe a ratio scale effectively. Additionally, categories that lack numeric representation do not provide the quantifiable relationships that ratio scales possess. By understanding the definition and the properties of the ratio scale, one can better appreciate its applications in data analysis, especially in fields requiring precise quantitative comparisons.