Pie Chart
A pie chart is a circular graph used to compare the relative magnitudes
of items by slices of the pie. The chart shows the percentage an item
contributes to the whole. Proportion items are arranged in descending
order starting with the largest at the top. It provides a quick, visual
indicator of relative importance of the items shown.
Example:
To see how they spent their money on vacation, George and Betty constructed
a pie chart as shown below:
Steps:
- Divide a circle (pie) into a number of wedges such that each wedge
corresponds to an item which represents a proportion to the total
number of items.
- Calculate the proportion of the item by dividing the item by the
total.
For example, the proportion for Gifts and Souvenirs shown on the previous
page is $220 in gifts divided by $2,000 total expenses = 0.11, or 11%.
- Convert the proportions into wedges by multiplying the proportions
by 360 degrees (Example: 0.11 x 360 = 39.6 degrees).
- Start with the largest wedge - the item with the biggest value,
beginning at the vertical position and going in a clockwise direction.
Measure off the wedge sizes with a protractor.
- When using pie charts, follow these rules:
- Order your categories from largest to smallest. The “other”
category, if one exists, is last, regardless of its size.
- Begin your first wedge with a starting line at the “12 o’clock”
or 0° (degree) position.
- Construct the remaining wedges in descending order by size and in
a clockwise direction with “Others” last.
 More
Quality Tools
|
