How does a frequency distribution summarize data for one variable?

A frequency distribution summarizes data for a single variable by organizing it into a set of nonoverlapping classes and recording the number of data values that fall into each category.1

For qualitative variables, this involves counting the occurrences within each distinct category, such as gender. For quantitative variables, the process requires defining specific numerical ranges or intervals; the distribution then tallies how many observations fall within those defined segments.1

Beyond simple counts, these distributions can also be expressed as relative frequency distributions, which represent the fraction or percentage of the total data set contained within each class. This method is highly effective for simplifying large data sets, allowing for easier analysis and the assignment of probabilities. These summaries can be presented in tabular form or visualized through graphical tools like a histogram or pie chart.12