Buzz
A pie chart is a visual representation used to compare statistical data. It’s named a pie chart because it resembles a circle split into smaller sections, similar to slices of a pie. A pie chart displays percentages in an easy-to-understand way but can also be a useful tool when presenting complex data. You can draw one manually with a compass, pencil, and colored markers, or use software like Word or free online tools to create a pie chart.
Steps
Calculate the Statistical Data
Write down each data point and list them in descending order. Start with the largest number in your data set. Write that number at the top of your list. Then write the second-largest number directly beneath it. Place each number on a new line to create a data column.
- You will find it easier to round numbers, so eliminate decimals where possible. For example, round 20.4 to 20 or 5.8 to 6. This will make calculations simpler without significantly affecting your results.
- For instance, if you’re drawing a pie chart showing the number of animals on a farm, you might list 24 cows at the top, followed by 20 pigs, and then 6 chickens.
Label each number to prevent forgetting them. You can either draw symbols or write labels based on the type of data your pie chart is representing. Position the labels next to the corresponding numbers on the same line. This will help you keep track of what each number stands for more easily.
- For example, you could write 'cows' next to 24, 'pigs' next to 20, and 'chickens' next to 6. You can also use small drawings to represent each animal or abbreviate their names as 'C', 'P', and 'CH'.
Add all the numbers to get the denominator. Draw a horizontal line below the data column and use a calculator to sum the numbers. Write the total below the line to get the denominator. This is the number you will divide each data point by to obtain the decimal result.
- The denominator is a mathematical term referring to the number below the fraction line.
- The idea is to divide each number in your data set by the denominator to get the decimal. This will provide the percentage of each data point in relation to the total. Then, multiply each decimal by 360 to find how much each section represents in the pie chart.
- For example, if the pie chart represents farm animals, you would add 24, 20, and 6 to get a total of 50. This total is the denominator.
Divide each number by the denominator to obtain decimal values. Use a calculator to divide each data point by the denominator. Write the decimal result next to the corresponding data. Each number should be less than 1, and the new column will arrange the results in descending order, with the largest at the top and the smallest at the bottom.
- If any result exceeds 1, it means an error has occurred. Each result must be a decimal.
- For the farm animal pie chart, 24/50 = 0.48 for cows, 20/50 = 0.4 for pigs, and 6/50 = 0.12 for chickens.
Tip: Decimals are essentially percentages. For instance, 0.44 is the same as 44%. This approach helps you visualize the magnitude of each data point. If exact accuracy isn’t critical, you can stop here and use the percentages to sketch the pie chart.
Multiply the decimals by 360 to get the angles for each pie slice. Use a calculator to multiply each decimal by 360. Write the result next to the decimal so that each set of numbers lines up with the corresponding original data.
- You may want to round the numbers up or down to obtain whole values. For example, you might round 56.6 to 57. Unless you are creating a specific type of pie chart that requires smaller divisions, rounding helps make the chart easier to read.
- For the farm animal pie chart, we have: 0.48 for cows x 360 = 172.8, 0.4 for pigs x 360 = 144, and 0.12 for chickens x 360 = 43.2. Round 172.8 to 173 and 43.2 to 43.
Add the numbers together to verify the result. Check your result by calculating the sum of the obtained values. If the total is 360, you have done it correctly. If it's 361 or 359, you may have rounded the numbers up or down incorrectly. If the numbers are entirely wrong, you have likely missed a step—review your calculations to pinpoint where the mistake occurred.
- In this example, 173 + 144 + 43 = 360, so you know the angles will form an exact circle in the chart.
Draw the chart
Use a compass to draw the circle. For absolute accuracy, take a mathematical compass and insert a pencil into the holder by sliding the pencil in. Position the pointed end of the compass at the center of the circle. Rotate the pencil while keeping the pointed end fixed to create a perfectly accurate circle.
- If you don't have a compass and don't care much about precision, you can use round objects like a pot lid or a bottle as the edge of the circle and trace around them.
- You can use a fountain pen if you prefer, but be prepared to start over if you make a mistake.
Tip: Create a circle as large as you desire! You only need to know the angles of each section that forms the chart, and they do not depend on the circle's size.
Draw a straight line from the center to the edge of the circle to form the radius. Keep the pointed end of the compass steady and move the pencil head to the edge of the circle. Once you loosen the hinge, pull the pencil straight down towards the pointed end to create the radius. Depending on the type of compass, you may need to mark the center of the circle after lifting the pointed end, then draw a line to the edge of the circle.
- This line could be vertical (12 or 6 o'clock direction on a clock face) or horizontal (9 or 3 o'clock direction on a clock face). The slices you create will go clockwise or counterclockwise.
Place the protractor on the radius. Position the small hole at the bottom of the protractor so that it aligns with the pointed end of the compass. Draw a straight line from the 90-degree mark on the protractor.
- The hole at the bottom of the protractor is called the sighting point and is used to create an accurate 90-degree angle by drawing a line aligned with the 90-degree mark.
Draw each slice, adjusting the sighting point each time you draw a line. Keep the sighting point aligned with the center of the circle and mark the first data point at the 90-degree position. Find this number on the outer part of the protractor and mark it. Then, draw a straight line from the marked point to the center of the circle. Each newly drawn line will form a 90-degree angle with the center of the circle for the next section you calculate.
- For example, if you’re drawing a farm animals chart, the first number would be 144. Add 144 to 90 to get 234. Mark the 234-degree position and draw a line. Rotate the protractor and use the newly drawn line to mark a new 90-degree angle. The next data is 43 degrees. Add 43 to 90 to get 133 degrees. Mark 133 degrees and draw a line to the center of the circle. The remaining section of the circle will be 173 degrees.
- You can use the bottom edge of the protractor and skip the step of adding the data to 90 if desired, but be aware this method is more prone to errors.
Color each section and add a key. Assign a key to the pie chart. Use different colors for each section to easily identify what each slice represents.
- Color the circle and the pencil marks with a permanent black marker if you really want the colors to stand out.
- You could also use patterns, like cow spots, to represent the number of cows in the chart!
Draw a pie chart on your computer
Create a pie chart in Excel using the charting tool. In your Excel spreadsheet, write each data label in the left column. Enter the corresponding data next to it in the same row. Highlight the labels and numbers by clicking and holding the mouse before dragging over all the labels and data. Release the mouse and click on the small icon that appears next to the numbers. Click on “Charts” and then select “Pie Chart” to create your pie chart.
- The order in which you list the data determines the order in which they appear on the chart. This is crucial if you are creating a sequential chart.
Click on the chart button in Word software to create a pie chart. In Microsoft Word, click on the 'Insert' tab at the top of the program. Click on the three bars labeled 'Chart' at the top of the page. On the left side of the window, click on the 'Pie' tab and choose the style for your pie chart. A new window will pop up with a set of rows, colors, and sample titles.
- Edit each label by changing the words to reflect what your data represents. Click on the chart's name to modify it so that the title reflects the chart's topic. Adjust the numbers next to each label to match your data.
- Any pie chart created in Excel or Word can be copied and pasted into PowerPoint.
- The pie chart you create in Word will look exactly like the chart made in Excel.
Use an online tool to create a pie chart if you don't have Word or Excel software. There are several free websites that allow you to input data and create pie charts. Look for free sites that let you customize the design and enter your own values. Some websites may require you to create a free account to download the chart directly, but you can always use a screenshot tool to capture the chart image.
- Two of the most popular online charting tools are: https://www.meta-chart.com/ and https://www.onlinecharttool.com. These tools allow you to control different design styles and enter your custom data.
- To use Meta-Chart, click on 'Pie Chart' on the homepage. Select the shape, outline, and background color. Click on the 'Data' tab to input numbers and the 'Labels' tab to add names for each data set. Click 'Display' to generate the chart.
- To use the Online Chart Tool, select 'Pie' from the dropdown menu at the top of the screen. Choose the form, colors, and design for your chart. Click 'next' to input the labels and data. Click 'next' again to choose a font, then click 'next' one more time to create the chart.
Things you will need
Statistical calculations
- Paper
- Pencil
Create a chart
- Calculator
- Mathematical compass
- Protractor
- Pencil
- Highlighter or colored pencil
