Pie Chart - Data Visualization for Businesses

Pie Chart

Data Visualization for Businesses

A picture is worth a thousand words. The ability to graphically represent your business data gives you the power to make informed business decisions quickly. (Microsoft.com, 2002) This representation must be visually appealing and easy to understand. By keeping it simple, it allows the broadest number of users to interpret the data, gain insights as to its meaning and facilitate communication on the data ultimately to solve the companyÐŽ¦s problem. Data visualization is the use of interactive, sensory representations, typically visual, of abstract data to reinforce cognition. (Wikipedia.org, 2005) That in itself is a method or technique of decision-making. To further break it down, the most popular and widely used tool of data visualization is the Pie Chart.

There are two types of pie charts. The first type is your standard Pie Chart and the second is the Exploded Pie Chart. The standard pie chart shows parts and their relationship to the whole. Pie charts are always based on a circle, since the circle provides a true visual concept of the whole hundred percent. The parts or ÐŽ§piesЎЁ of the chart represent percentages of the whole. The Exploded Pie Chart is nearly identical to the standard with the exception that one ÐŽ§pieЎЁ is visually separated from the rest for emphasis. Pie charts are created with the help of a compass, protractor, circle stencil, can or jar and a ruler for drawing in the segmented pies. A pie chart should always be drawn in order from the largest to the smallest pie in a clockwise fashion. The pies have percentages and data labels above them; then you do not have to keep checking the legend to interpret the graph. In Figure 1 is the method used to create a pie chart and an example of one complete.

Figure 1

Problem: A pizza parlor owner polled their patrons on what music they would like to listen to while waiting in line and eating in his establishment. He would like to have the radio playing and needs to know what music genre would be conducive to sales and preferred by his patrons. Here are his findings.

Sample size: 100 customers

Rap: 50 Alternative: 25 Rock and Roll: 13 Country: 10 Classical: 2

50 „i 100 like Rap = 50%

Then for drawing a proportionate pie chart:

Percent „i 100 x 360 degrees = the # of degrees

**Circle = 360„a

ÐŽK Therefore Rap will occupy 180„a of the circle

1. Draw a circle with your protractor or stencil

2. Starting from the 12 oÐŽ¦clock position on the circle, measure an angle of 180 degrees with your protractor. The rap pie should make up half the circle. Mark off the radius with the ruler.

3. Repeat that process with each remaining pie and drawing in their radius according to their percentage of 360 degrees.

The pie chart in Figure 1 quickly tells you that the majority of the patrons like rap best, and the remaining students prefer alternative, then rock and roll, then country and ending with classical music. Simply and quickly we are able to see that the majority of the restaurantsÐŽ¦ patrons prefer rap music. Pie charts work well when the values of the percentages of the whole differ greatly from each other. In other words, you do not want your pie values to be within one or two digits from each other, which would be indistinguishable on the chart to the naked eye. Another moniker for pie charts is: do not use a pie chart when there are more than six parts to the whole. Having too many values for comparison on the