Pie diagram
Also called: Divided circle diagram, Pie chart · Topic: Graphical Representation of Data and Thematic Maps · NCERT: Class 12, Ch 3 "Graphical Representation of Data"; Class 12, Ch 4 "Spatial Information Technology"
Meaning
A pie diagram, also called a divided circle diagram, shows a total as a full circle. The circle is cut into slices (sectors), each sized in proportion to one part. Angle of a slice = (value of the part ÷ total) × 360, or simply percentage × 3.6. To draw it, choose a radius of 3–5 cm and draw one radius line. Then measure the angles clockwise, starting with the smallest. If you start with the biggest, small errors build up and the small angles become hard to plot. Pies work poorly when there are many small parts.
Example
NCERT draws India's exports by region in 2010-11 (Economic Survey 2011-12). Asia and ASEAN had 56.2%, giving 203°. Europe had 20.2% (73°), America 14.8% (53°), Africa 6.5% (23°) and others 2.3% (8°).
Don't confuse with
- Compound bar diagram: this also shows the parts of a total, but inside a bar. That makes it easier for comparing several totals side by side.