Chapter 9 SECTOR CHARTS

A SECTOR chart presents data in the form of a circle. The circle is divided along its radii so that the angle of each section is proportional to the factual data it represents. Other terms used for sector chart are: pie chart, divided circle. In practically every instance in which material is presented in a sector chart, the same information might also be presented in bar charts. See Chapters 10 and 12.

From D. P. Donnant, "StatUtical Account of the United State* of America," 1805, Oeeenland Ai Nofria, London. The Chart Wa« Made by William Playfair. SCALE .5

Statistical Representation of the United States of America in 1805.

1. This, so far as is known, was one of the first sector charts. William Playfair, the man

who invented the method, called it a "divided circle."

2. In Statiatical Breviary, 1801, William Playfair presented a group of circles whose areas

were equal to the areas of the countries they represented. The circle representing the Turkish Empire was divided into 3 sections. Since this preceded the illustration above in point of time, it may have been the first sector chart.

GRAPHIC PRESENTATION

A. Employment and Unemploymenf Experience of 129 Displaced Hand Cigar Makers in Manchester, N. Y., as Recorded Five Years After the Lay-off.

1. Divisions within divisions are possible

in the sector chart. Here two categories, employed and unemployed, are further divided so that the circle is in reality divided into four parts.

2. Shading pieces of the sector chart