Charts

Pie Charts

Pie charts are generally used to show proportional data and can help a user understand the contribution of parts to a whole. Pie charts should only be used to represent data that can be placed into distinct categories and should not consist of more than 6 slices.

Always sort the data values in ascending or descending order and include value and category labels for the slices.

DO

DON'T

Column and Bar Charts

Use column and bar charts for direct comparison of data or to show data over time when the number of time intervals is small.

Sort columns in systematic order, either by size of value or by sequential categories (e.g. sorting by year, alphabetization).

DO

DON'T

Don't use multiple pie charts when comparing multiple sets of data. Use a column chart instead.


While column and bar charts are similar, they cannot always be used interchangeably due to the difference in their orientation.

Column Charts

Use column charts to compare values across sequential and time-based categories, emphasize specific high or low values, or display data with negative and positive values.

Sort order impacts the way information is interpreted and can help highlight information. Use a sequential sort order if categories are related to time. Sort in ascending or descending order to show a trend, rank values, or emphasize the largest or smallest value in a data set. If the user will not expect to see categories in a specific order, sort alphabetically to increase discoverability.

Category labels placed along the horizontal axis are helpful when users expect to view categories in a specific sequence

A column chart sorted in ascending order will draw attention to the largest column

A column chart is useful for displaying negative and positive values. Sorting by alphabetical order helps the user locate specific categories.

Bar Charts

Use bar charts to compare values across categories that are not sequential or time-based. If labels are long or if there are many categories, a bar chart is more effective than a column chart because each label will have sufficient space regardless of the number of categories.

Sort in descending order to emphasize the largest value in a data set. Sort in alphabetical order to help the user scan for specific categories, especially when there are many items.

A bar chart sorted descending order will draw attention to the largest category

DO

Use bar charts to maintain readability when labels are long or when there are many categories

DON'T

Don’t use column charts when labels are long, especially if label text is truncated or rotated


Line Charts

Line charts are best used for presenting data over time and are more effective than bar charts for presenting many data points. They are also more effective for displaying data in scenarios where the differences between data points are small.

Conventionally, the x-axis contains the categories of time, and the y-axis the frequencies of the measured data.

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DON'T

Charts with more than 5 lines tend to be confusing unless the lines are well separated

DO

A line chart’s y-axis values are automatically scaled to fit the line chart, which increases the visibility of relatively small differences in data values.

DON'T

Don’t use a column chart when the differences between values are small. Column charts use forced-zero scaling, which makes it difficult to distinguish between similar items when their values are large.

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