Why Do Researchers Commonly Use Intervals When Representing Frequency Distributions

Essay

Why do researchers commonly use intervals when representing frequency distributions for interval-ratio variables, and what principles should guide them when constructing such frequency distributions?
• Interval-ratio variables tend to have many possible values. Aggregating a range of values helps provide a more manageable way to understand how the variable is distributed rather than showing the frequency of every possible score.
• Scores should be grouped to maximize clarity and ease of comprehension. A general guiding principle is that one should balance detail (a large number of narrow categories) with compactness (a smaller number of wide categories).
• Another general rule for using intervals is that they should be equal in size.