Sektordiagramm

Sektordiagramm, in English commonly known as a pie chart, is a circular diagram used to illustrate numerical proportions in a dataset. It consists of sectors (wedges) of a circle, each sector representing a category's share of a total.

The central angle of each sector is proportional to the category's percentage of the whole: a full circle has 360 degrees, so a category with p percent has an angle of p/100 × 360 degrees. Sektordiagramm is often drawn with a legend or labels for each sector and may use colors to distinguish categories.

Variants include the donut chart, which leaves a blank center, and exploded pie charts, where sectors are slightly separated to emphasize a particular category. In interpretation, the reader compares sector sizes to assess relative importance or prevalence.

The diagram is most effective when the number of categories is small (roughly up to five to seven) and differences are not extremely subtle. It is less suitable when precise comparisons are required or when there are many small categories, as small sectors can be hard to discern.

History and usage: circle graphs were popularized in the 19th century; William Playfair introduced circle graphs in his statistical works. In modern practice, the Sektordiagramm is widely used in reports, media, and educational materials to show shares such as market segmentation, survey results, or demographic composition.

Related concepts include Kreisdiagramm and Donut chart.