Economics · Ch 4 — Presentation of Data

Pie Diagram

4.5.1.2

Pie Diagram

A pie diagram (or pie chart) is a component diagram in the shape of a circle whose area is divided among the components in proportion to their sizes. Straight lines drawn from the centre to the circumference cut the circle into as many sectors as there are components.

Pie charts are drawn from percentages, not absolute values: each category's value is first written as a percentage of the total. The whole circle is treated as $100$ equal parts, so each one per cent corresponds to

\frac{360^\circ}{100} = 3.6^\circ.

The angle a component makes at the centre is found by multiplying its percentage by $3.6^\circ$ . For example, for the working status of India's population in 2011 (Table 4.8 below):

Table 4.8-tableDistribution of Indian population (2011) by working status (crores)

Status	Population (crore)	Per cent	Angular Component
Marginal Worker	12	9.9	$9.9 \times 3.6^\circ \approx 36^\circ$
Main Worker	36	29.8	$29.8 \times 3.6^\circ \approx 107^\circ$

Data that a component bar diagram can show can equally be shown by a pie chart, once the absolute values are turned into percentages. The radius makes no difference to the meaning — only the proportions of the sectors matter.

A person reacting "This is fantastic!" beside a small 3-slice pie chart of Marginal Worker (12), Main Worker (36) and Non-worker (73) crore.

Drawn by us to help you understand the concept clearly, and verified to make sure it's accurate. For exams, practice from your textbook's own diagram.

Our own line-art cartoon (not traced from NCERT), drawn with the correct 12/36/73 crore split from Table 4.8 (the numbered Fig 4.4 just above had a printing misprint on this exact figure, corrected separately — this cartoon was never affected). A pie chart turns the same working-status data Figure …

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Figure 4.4Pie diagram for different categories of Indian population according to working status 2011.

Fig. 4.4 — Pie diagram for different categories of Indian population according to working status 2011.

Drawn by us to help you understand the concept clearly, and verified to make sure it's accurate. For exams, practice from your textbook's own diagram.

A pie diagram: the full circle ( $360°$ ) is India's 2011 population by working status, each sector's angle proportional to its share. Non-workers form the largest slice ( $60.3\%$ , ~ $217°$ ), main workers next ( $29.8\%$ , ~ $107°$ ) and marginal workers the smallest ( $9.9\%$ , ~ $36°$ ). Read the sector sizes to compare shares of a whole. (One printed slice label rea …

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