visual explanations with graphs

Connie Malamed

@elearningcoach

theelearningcoach.com

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A graph makes numbers concrete and serves as a cognitive aid. Graphs show the shape of the data and can be processed in parallel. Source: BBC.

Benefits of Visualization

Makes the abstract concrete

Serves as a cognitive aid

Structures information

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Position Position: nonaligned Length Direction Angle

Area Volume Curvature Shading Saturation

Cleveland and McGill, 1984

Cleveland and McGill did research on which basic perceptual tasks are most likely to result in accurate judgments. So, judging position is more accurate than judging area. Tasks with the same border color provide equal perceptual accuracy.

Comparisons

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Bar Chart

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When your main purpose is for the viewer to compare values, use a bar graph or a pictograph. According to the research by Cleveland and McGill, perceiving the variation in position on a common scale is relatively easy for people to do.

Bar graphs are typically used for time series data, but you can also use them to report other categories of data. Use a contrasting color or color saturation for the focus bar (if there is one). Source: Visual Design Solutions (my book).

Bar Graph

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Grouped Bar Chart

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Use a grouped bar graph when you need to compare two or more variables in a category.

Pictographs

What problem do you see with this graph?

Answer: There is not enough differentiation between the colors.

Bar Graph

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3D Chart

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3-D bar charts can make graphs harder to read because the depth cues that show the third dimension can be distracting.

Bar Graph

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Stacked Bar Chart

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Stacked bar graphs are divided into independent variables or subgroups. They show the relationship of the subgroup to the total. They can be a bit difficult for making comparisons.

Trends

To show how a quantity progressively changes over time, a line graph is a good choice. This format is more effective than a bar graph when there are many data points to display. Source: Visual Design Solutions.

Do you see the difference between the quantities in this pie chart? Probably not, because it is difficult to judge area with accuracy. Use pie charts (if at all) for impact, not accuracy.

Another example of how it is difficult to judge area with accuracy.

A Side Note: This type of visualization is pretty, but is not a true information graphic. It is not a cognitive aid. It does not help us glean insights. The next slide shows another visual in this same category.

Again, this is not an information graphic in the true sense of the word. Nothing is gained from viewing it … no original or new insights.

THANK YOU

Connie Malamed

@elearningcoach

theelearningcoach.com