Which is the best type of graph to show proportions of a whole?

A pie chart is the best type of graph to show proportions of a whole because it visually represents data in a circular format, where each slice corresponds to a category's proportion relative to the total. The size of each slice effectively conveys the part-to-whole relationship, making it easy for viewers to quickly grasp how different categories contribute to the entire dataset. This is especially useful when there are a limited number of categories, allowing for clear and immediate understanding of the distribution.

Other graph types, such as line, area, or column, are typically used for different purposes. Line graphs are ideal for showing trends over time, area graphs emphasize the total volume under a curve, and column charts are effective for comparing quantities across categories but do not inherently communicate the concept of parts of a whole as effectively as a pie chart does. Therefore, for depicting proportions specifically, the pie chart is the most appropriate choice.