Which method is effective in comparing categorical variables when visualizing data?

Using pie charts to compare categorical variables is effective due to their ability to show proportional relationships within a whole. Each segment of a pie chart represents a category, and the size of each segment corresponds to the proportion of that category in relation to the total. This visual representation allows viewers to quickly assess which categories are more prevalent or less pronounced at a glance.

Pie charts work particularly well when there are a limited number of categories, as too many categories can make the chart cluttered and difficult to read. They are best utilized when the emphasis is on showing the composition of a dataset rather than on specific values or trends over time.

In contrast, line graphs are better suited for displaying data points over time or continuous data, scatter plots are used to show relationships between two continuous variables, and histograms represent the distribution of numerical data rather than categorical comparisons. Each of these methods serves different analytical purposes, but for categorical data specifically, pie charts excel in providing a clear, visual comparison of the parts to a whole.