Emberex: Data Visualization Guidelines

Bar Chart

A bar chart presents grouped data with rectangular bars sized proportionally to the values they represent. The bars can be plotted vertically or horizontally.
Standard Bar Chart
PRODUCE UNITS SOLD
Horizontal Bar Chart
PRODUCE UNITS SOLD
Stacked Bar Chart
PRODUCE UNITS SOLD BY STORE
Histogram
DISTRIBUTION OF PRODUCE SALES

A histogram is a graphical representation of the distribution of numerical data. It is basically a bar chart showing strictly numerical values.

What's the difference between a bar chart and a histogram? Bar chart data is grouped by category, histogram data is grouped by a quantitative variable. Because a histogram represents a continuous set of numerical values, the bars should touch.

Area Chart

An area chart is similar to a line chart, except the area below the line is filled to indicate volume. Different volumes can be overlapped. When multiple variables are compared, the fill color should be transparent so data is not hidden.
CONTAINERS OF PRODUCE PURCHASED

Stacked Area Chart

Alternatively, an area chart can compare values by stacking them. This also allows you to relate each value to the total.
CONTAINERS OF PRODUCE PURCHASED

Scatter Plot

A scatter plot displays a series of points. The position of each point is determined by its relationship to the horizontal and vertical axis.
GEYSER ERUPTIONS

Bubble Chart

A bubble chart uses the area of a circle to add a third axis of information to a representation of a series of values.
PARTS SOLD
In this example, time, cost, and quantity are represented. In this case, the area of the circle represents the quantity of parts. Further below, bubbles are overlaid on a map showing quantity in relation to location.
PARTS SOLD
Bubble Map
PART SALES

Pie Chart

A pie chart is a circle divided into sections proportional to percentages. A pie chart works best when comparing only 2-3 values, as it becomes difficult to distinguish proportions when the number of values increases. If more than 3 values need to be displayed, a bar chart is probably a better option.
Standard Pie Chart
PERCENTAGE OF PIES SOLD
Donut
JULY
Nested Donut
A donut chart is a pie chart with the center removed. Both are equally delicious when used in moderation. The knocked out center gives additional space for labeling or nesting other charts while maintaining the proportions of the values.
Half Pie
Half Donut
JULY
Skewed 3D Pie
Skewed 3D Pie
3D Pie (non skewed)
Non-skewed 3D Pie
Skewing a pie chart with 3D effects should typically be avoided. This kind of effect skews our perception of the data, making it less accurate and less effective. Portions of a pie chart can be called out by applying non-skewing depth. When in doubt, it is best to keep pie charts flat and circular.
Polar Area Diagram
The polar area diagram is like a pie chart, but the sectors are the same angle and differ by how far they extend from the center. This chart type is best used to plot cyclical data.

Radar Chart

A radar chart is a graphical way of displaying data with three or more variables. Each axis starts from the same point. Like the polar area diagram, this chart works well for comparing cyclical data.
NUMBER OF PIES SOLD

Keep your charts simple

Although it can be tempting to embellish charts to make the data look more important or a presentation more flashy, a good chart should be as simple as possible and easy to read. Here is an example of how not to do it, followed by suggestions about how to make it better.
Don't do this
Don't do this chart

Chart issues

  • Color coded date key is overly complicated and serves no value.
  • Color key is located in the chart and competes with actual data.
  • Chart has unnecessary decoration that distract from data.
  • Numbers above bars miss the point of having a chart.
Better
TRENDS IN FRUIT PRODUCTION

Improvements

  • Placement of dates and fruit type are switched.
  • Visual Structure is simplified and highlights data.
  • Bars are distinct colors with ample contrast.

Issues

  • Bar chart is not the best way to represent the data.
Best
TRENDS IN FRUIT PRODUCTION

Improvements

  • Bar chart replaced with a line chart, which better suits the data.
  • The chart now tells a clear and accurate story.

Get Creative

The charts discussed here are just the tip of the iceberg. Each of these chart types was originally created for a specific research need. If you can’t find a chart that represents your research data well, don’t hesitate to think outside of the box and make something new.

Give us a call us at (541) 687 5778 or email us at [email protected]. We would love to discuss your next research project.

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