In the year 1901, William Playfair, a Scottish engineer, and political economist invented the pie chart.
A pie chart is a circular chart divided into slices. The slices illustrate the proportion based on percentages. The slices need to be mutually exclusive; they cannot overlap. The data should not only sum up to a meaningful whole but the values should be categorized such that they are not counted several times. Get more info to Learn tableau training
A pie chart should be used in the following circumstances.
• To show the relationship of a part to the whole.
• To display data that could otherwise be represented in a small table.
• When data is available in six or fewer categories.
• When your data set is very small and does not need to show progression over time.
• When data is either nominal or ordinal. Data in a nominal category is one in which it can be classified based on descriptive or qualitative information, such as country residing in, workplace location, etc. Data under the ordinal category is one in which it can be ranked. For example, participants can be asked to provide ratings such as excellent, very good, good, poor, very poor, etc. to measure the effectiveness of a learning program.
Consider two features while reading a pie chart:
• The angle that a slice covers
• The area of a slice.
Pros Few benefits of pie charts are stated below:
• Simple to read if there are only a few categories represented on the pie chart.
• Simple to understand even by an uninformed audience. Pie charts are visually simpler than other types of graphs, and it can be easily understood due to widespread use in business and the media.
• Does not require a lot of explanation when used in a report or presentation.
Cons
• The main purpose of the pie chart is to be able to perform a relative comparison. The purpose gets defeated as it is not easy to decipher the angles created by the slice.
• Is ill-suited if there is too much data (read categories) to be represented on the pie chart.
• Do not easily reveal exact values. Pie charts fail to reveal key assumptions, causes, effects, or patterns. Learn more at tableau online training
If you still decide that a pie chart is the right data visualization for what you are trying to achieve, look at the following five tips before throwing that pie into your presentation:
• A pie chart with more than six individual segments is going to look too cluttered and lose its visual impact.
• Order your segments from largest to smallest. Do not make people work to see the scale.
• Do not try to make pie charts more visually appealing by adding effects like shadows or 3D perspectives. These make it more difficult to understand the data.
• Make sure everything adds up to 100 percent.
• Put a name or number onto each segment of your pie chart. A surprisingly large portion of the population is color blind, so the chart is meaningless to them without labels.
Step 1
Select "Pie" in the marks card. Notice that “Angle” is added as another feature in the marks card
Step 2
Drag the dimension “Customer Segment” from the dimensions area under the data pane and place it on “Color” on the marks card We have data for four segments, namely, “Consumer”, “Corporate”, “Home Office” and “Small Business”. The pie chart, therefore, is split into four slices, one for each segment. Notice that all the slices are the same size. The reason is that up to now we have not added any measure to the “Size” or “Angle” feature on the marks card.
Step 3
Let us have the size of the slices determined by the amount of “Sales” made in each “Customer Segment”. Drag the measure “Sales” from the measures area under the data pane and place it on “Size” on the marks card. Notice the change in the size of the slices. The size is as per the “Sales” made in each “Customer Segment”.
Step 4
Drag the measure “Profit” from the measures area under the data pane and place it on “Angle” on the marks card. The angle of the slices is now as per the “Profit” made in each “Customer Segment”.
Step 5
Drag the measure “Sales” from the measures area under the data pane and place it on “Label” on the marks card.
Step 6
Let us transform the sales figures into percentages. Right-click on measure "Sales" on the "Label" to bring up a drop-down menu. Select “Quick Table Calculation”.
Selecting "Quick Table Calculation" brings up another set of options. Select “Percent of Total”
The displayed labels on the pie chart in the worksheet/view changes to reflect the percentage of the total.
If you happen to add up the percentages of each slice in the pie, it should add up to 100%. Let us validate.
(19.68 + 19.28 + 37.34 + 23.70) = 100
