Pie Chart

A pie chart is a graphical representation of data as a disk divided into wedge-shaped ‘pieces’ or ‘slices’ whose sizes are proportional to the relative frequencies of the categories they represent. Because pie charts are most useful when they include only a small number of categories, they are most often used to display the relative frequencies of a categorical data set. Pie charts are a logical choice for graphical presentation when the focus of interest is on the relative frequencies of the data—that is, how much of the whole each category represents, rather than the absolute frequency of each category (in the latter case, a bar chart would be more appropriate).

Florence Nightingale, a founder of modern nursing, was also well versed in statistics. She invented ...