1. Circle Graphs
A graph made of a circle divided into sectors.

2. A circle graph/pie chart is a way of summarizing a set of categorical data or displaying the different values of a given variable (e.g., percentage distribution).
This type of chart is a circle divided into a series of segments. Each segment represents a particular category. The area of each segment is the same proportion of a circle as the category is of the total data set.

3. Parts of a Circle Graph
Graph Title – the title tells what the graph is representing.
Sectors – Each sector is one part of the whole circle.
Sector Labels – Each label tells what the sector represents.
The Perfect Pizza
55% cheese
15% sauce
30% pepperoni

4. Circle graphs/pie charts usually show the component parts of a whole
Circle graphs/pie charts usually show the component parts of a whole. Often you will see a segment of the drawing separated from the rest of the pie in order to emphasize an important piece of information.

5. The circle graph/pie chart below clearly shows that 90% of all students and faculty members at Avenue High School do not want to have a uniform dress code and that only 10% of the school population would like to adopt school uniforms. This point is clearly emphasized by its visual separation from the rest of the pie.

6. Why circle graph/pie chart?
The use of the circle graph/pie chart is quite popular, as the circle provides a visual concept of the whole (100%).
Circle graphs/pie charts are also one of the most commonly used charts because they are simple to use.

7. Despite its popularity, circle graphs/pie charts should be used sparingly for two reasons.
First, they are best used for displaying statistical information when there are no more than six components only—otherwise, the resulting picture will be too complex to understand.
Second, circle graphs/pie charts are not useful when the values of each component are similar because it is difficult to see the differences between slice sizes.

8. A circle graph/pie chart uses percentages to compare information.
Percentages are used because they are the easiest way to represent a whole. The whole is equal to 100%.

9. Constructing a circle graph/pie chart
A circle graph/pie chart is constructed by converting the share of each component into a percentage of 360 degrees. In Figure 2, music preferences in 14- to 19-year-olds are clearly shown.

10. The circle graph/pie chart quickly tells you that half of students like rap best (50%), and the remaining students prefer alternative (25%), rock and roll (13%), country (10%) and classical (2%).

11. Labeling the segments with percentage values often makes it easier to tell quickly which segment is bigger.
Whenever possible, the percentage and the category label should be indicated beside their corresponding segments. This way, users do not have to constantly look back at the legend in order to identify what category each color represents.

12. The circle graph/pie chart above conveys a clear message to the user—that 88% of all students in the World Religions class celebrate Easter.
We can easily tell what the message is by simply looking at the accompanying percentages.
Unfortunately, the category labels are too long to fit beside the pie segments, so they had to be placed in the legend. Ideally, these labels would also accompany the pie segments.

13. It is more difficult to understand the message behind Figure 4 because there are no percentage figures given for each slice of the pie.
This is why it is important to label the slices with actual values.
The user can still develop a picture of what is being said about the type of pets sold by this store, but the message is not as clear as it would have been had the parts of the pie been labeled.

14. In the circle graph/pie chart below, the legend is formatted properly and the percentages are included for each of the pie segments.
However, there are too many items in the circle graph/pie chart to quickly give a clear picture of the distribution of movie genres.
If there are more than five or six categories, consider using a another graph to display the information. Figure 5 would certainly be easier to read as a bar graph.

15. How to make a circle graph
Tip! When drawing a circle graph/pie chart, ensure that the segments are ordered by size (largest to smallest) and in a clockwise direction.
Using a compass, draw a circle large enough to show all of your data.
Determine how many sectors you will need in your graph. You will need to know the percentages of the whole of your data. Try to make the sector sizes look as close to the percentage of the circle as the percentage of your data.
Label each sector and give your graph a title.

16. Using the data, make a circle graph/ pie chart
Favorite food
Number of votes
Pizza 10
Chicken 8
Spaghetti 5
Fish 2

17. You must now change the numbers to percentages
You must now change the numbers to percentages. To do this, change each number to a fraction.
10/ / / /25
Then divide the numerator by the denominator.
10/25= /25= /25= /25=.08
Then multiply the answer by 100
.40*100=40%
.32*100=32%
.20*100=20%
.08*100=8%
Now you are ready to draw your circle graph.

18. First you will need to divide your circle into approximate sectors to represent each percentage. Label each sector with the appropriate name and percentage.
Chicken 32%
Pizza 40%
Spaghetti 20%
Fish 8%

19. Favorite Lunch Foods Chicken 32% Pizza 40% Spaghetti 20% Fish 8%
Finally, give your graph a title.
Favorite Lunch Foods
Chicken 32%
Pizza 40%
Spaghetti 20%
Fish 8%

20. Now you know how to create a circle graph/pie chart… Now what do you do with the information
You can use the percentages to determine how many people are you referring to.
Let’s look at our last example again.

21. Favorite Lunch Foods Chicken 32% Pizza 40% Spaghetti 20% Fish 8%
If 25 students are surveyed and this graph is a representation of the data. You can use the number of students times the percentage to see the actual number of student for each category.
The students who said chicken was their favorite lunch food.
32% of 25 = 8 students
Favorite Lunch Foods
Chicken 32%
Pizza 40%
Spaghetti 20%
Fish 8%

22. 5 Favorite Lunch Foods Chicken 32% Pizza 40% Spaghetti 20% Fish 8%
The students who said spaghetti was their favorite lunch food.
20 % x 25 = 5
Favorite Lunch Foods
Chicken 32%
Pizza 40%
Spaghetti 20%
Fish 8%

23. Mr. Sobieski asked his class to vote on where they would most like to go on a field trip. The choices he gave them were: history museum, science museum, art gallery, and nature preserve. All 30 students cast one vote each. The pie graph below shows the results.
How many students chose the history museum?
How many students chose the science museum?
3. How many students chose the nature preserve or the art gallery?
FIELD TRIP VOTES

24. Vehicles Sold at a Dealership (Number per Type)
What percent of the sales were Sport Utility vehicles?
What percent of the sales were Minivans?

25. Given the table below, create a circle graph which represents the same information.
Favorite drinks
Drink
Number of votes
Lemonade 15
Cola 10
Cherry 5
Pepsi 20
Fanta
Shares of Stock Owned by an Investor
Type of Stock
Number of Shares
Coca-Cola 8
Pepsi 1
IBM 4
Exxon GM 20
Sneakers Sold for November 1997 at the Shoe Source
Brand Name
Number Sold
Adidas
150
Nike
192
Reebok 60
Asics
108
Other 90