Displaying Data:

Pie Chart

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Description: A pie chart is used to show visually the proportions of parts of something being studied. The area of each slice of the pie shows the slice’s proportion to the entire category being studied and to the other slices. A pie chart shows data at one point in time, like a snapshot; it does not show change in data over time like a line chart does.

How to Use it: Decide on the overall category and then the subcategories. (For instance: Overall – Pets, Subcategories – Fish, Dogs, Cats, Exotic). Calculate the percent of the total for each subcategory. Change each category into degrees relative to a circle. (i.e. 12% X 360 = 43 degrees). Then divide the circle into appropriately sized segments and label them.

Resource: http://eagereyes.org/techniques/pie-charts

Things to think about: Color! What colors will work best given your infographic. Is there a creative way you’d like to present the pie chart? Does it make sense to have lots of slices (subcategories) or just two? Keep in mind that creativity is great as long as you don’t misrepresent the data.

EXAMPLE: There are 400 animals in a study. There are 10 monkeys, 50 gorillas, 80 fish, 60 Tucans, 120 songbirds, 35 snakes and 45 lizards.

Overall Cateogory:

Possible subcategories:

Chart:

Bar Graph

Description: Unlike a histogram, a bar graph has two axis. An independent and dependent variable. Bar graphs are used to compare data, especially numbers that might be too similar to understand in a pie chart. Bar graphs can show change over time, but usually a line graph is better for time, unless they are distinct categories (i.e. profits in a year).

How to Use them: You need to decide on categories to go across the horizontal axis. These can be related or less related (i.e. years v. types of jobs). They do not have to encompass a “whole.” The vertical axis should be a scale that works for all the categories, usually you are counting something.

Think about: What message do you want to send with this graph? Is it supposed to show a trend? Compare things? You can manipulate the graph to make your point without giving incorrect information. You MUST label the axis.

Histogram/Frequency Graphs

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Description: A histogram has one axis that is labeled with categories. Then each bar counts how many things in that category. Histograms and Bar graphs are similar, but Bar graphs have a wider possible use. Histograms should be used to show trends or compare data. The categories should be related and if they over time they should be evenly spaced.

How to use them: Decide on your categories (buckets). Then count the number of things in each category. The bars must each have the same scale. You must label how many things are in each bucket, unless you are just showing a trend. But without a scale you run the risk of misrepresenting comparisons (a histogram that shows the difference between 0.1 and 0.5 will be just as large a gap as 100 to 500 things).

Think about: Is there a creative way to draw your bars? How do you want to organize your buckets if they are not time?

“Fill ‘er up” Graphs

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Description: These are a different kind of “pie chart.” They involve showing part of a whole, but with only two categories. For example “Amount of Homework I have” would be the overall category and “amount I’ve done” and “amount I’ve left to do” would be the subcategories. These graphs are fun because you can make the shape you fill up anything you like.

How to Use: Pick a shape you will “Fill Up” and the overall category and the subcategory. The subcategories should always make sense with filling something up. You wouldn’t have animals and then monkeys and dogs. Because you aren’t filling up “animals” with monkeys and have dogs left. But you could do “Pets” and “have a pet,” “don’t have a pet.” To make the graph find the percentage of the filled part to the whole. Then find where that percentage is on the object.

Things to think about: What do you want to fill up? What picture is relevant to your infographic? Does a “fill ‘er Up” graph really make sense instead of a pie chart here? Are you actually filling something up?

Showing amounts/Pictogram

Description: Sometimes you’d like to show the amount of something, but you want to actually count it out, show what the number is. These can be helpful for either small numbers or very large ones. Numbers that are hard to visualize in other graphs. They also help diminish size distortion, when you are counting something the size of the number will be obvious.

How to use: Usually these are shown by assigning a value (1 or otherwise) to a graphic and then repeating that graphic as many times as needed.

Things to think about: Why is it important to show the value of this number? Why is this method better than a bar graph or pie chart? What image are you going to use? Why?

Line graph

Description: A line graph is specifically for showing a trend over time. Nothing else! It has two axis, the independent (horizontal) axis is always time. These should be used for continuous data, not chunks or categories. The dependent axis will most often count something.

How to use: Decide on your time scale. Make sure your data is continuous. Plot your data points and then connect them. A line graph is always at least a little bit predicted data. This is because you are graphing continuous data, but your data points will not be continuous.

Things to think about: If I read the graph at any point, will the data make sense? Am I trying to show a trend? What is the point I’m making with this graph? Why a line graph and not a bar graph?

Misrepresenting Data Resources:

http://faculty.atu.edu/mfinan/2043/section31.pdf