After completing this unit, you should be able to:
This unit is intended to review and clarify the uses for, and the similarities and differences between, tables, bar graphs, and circle graphs. Often it is difficult to determine the most appropriate way to visually display data. You may wonder whether you should use a table, circle graph or bar graph to display the given data. This section will help you learn how to choose the most appropriate graph, depending on the information you want conveyed.
While each representation has its strong points, each also has limitations. When we are representing data, it is important to determine which form is better. This will depend on what we want readers to be able to see.
Now let's look at an example, to help illustrate this discussion.
Given the following table, draw the appropriate graph for each case, then answer the questions below.
Brand Name  Number Sold 

Adidas 

Nike 

Reebok 

Asics 

Other 

Total 

If we want to make a graph that simply shows this data, it really wouldn't matter which type of graph we chose. The choice of graph depends on what we want to emphasize.
RECALL: Circle graphs are best used to compare parts to a whole, while bar graphs are most effective in comparing among groups.
We are asked to show each company's sales. A bar graph which has the advantage of demonstrating countable data, facts about groups, and patterns is the best choice. 
Sneakers Sold This Month 
We are to asked display Nike's role in the entire shoe industry. In other words, we want to display Nike as a part of the whole industry. The part to whole is best shown by using a circle graph. 
Sneakers Sold This Month (Total Sold = 100 Shoes) 
The overriding differences are:
In the circle graph, the five companies are presented as parts of the total industry, while the bar graph displays each company as its own entity, in competition with one another.
Both displays are different from the table. They each visually display the data that is in the table, but they do it using two different methods. The circle graph utilizes the total from the table while the bar graph does not. Notice that each sector of the circle graph is the same proportion to the entire circle as the number of sales for that industry is to the entire amount of sales. The bar graph does not utilize the total from the table, but simply gives a visual listing of the information in the table. The number of sneakers sold per month are the same in the table as the height of the bars in the bar graph.
If you were asked to make exact calculations based on this data, a table would be best since you may take precise values directly from a table, without worrying about inaccuracies in the construction or reading of a graphs. A table would be the safest method of abstracting data for computations.
Now try the practice below. This unit includes one practice problem with detailed solutions. It is recommended that you read through this practice carefully, to help strengthen your sense of the distinction between, and the use of, circle and bar graphs.





