Which Chart to Use

Data Types and Scales

• Most 2D charts contain 2 types of data:
◇ Quantitative - the numbers
◇ Categorical - the categories those numbers fall into
• Different types of categories are:
◇ Regions - north, south, east, west or Asia, Americas, Europe etc.
◇ Departments - sales, marketing, operations etc.
◇ Time - days, wekks, months, quarters, years etc.
◇ Bands / Bins - 0-10, 11-20, 21-30 etc.
• Categories fall into one of 3 types:
◇ Nominal - think ‘name’
◇ Ordinal - think ‘order’
◇ Interval or Ratio - think ‘groups’

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What's Your Message

• There are 7 types of quantitative messages
◇ Nominal comparison - comparing departments, regions etc.
◇ Time-series - trend over time
◇ Ranking - largest to smallest, smallest to largest
◇ Parts to the whole - actual vs. budget/target, regional share of overall revenues
◇ Deviation - data compared to the norm or expected result expressed as the difference
◇ Frequency distribution - counts of data per interval or range
◇ Correlation - comparison of two paired sets of measures to understand the relationship between the measures
• If you have multiple messages, consider building multiple charts or making the charts dynamic so the user can choose the view

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Which Chart to Use

Message	Chart	Remarks
Nominal Comparison	Column or Bar charts
Time Series	Line or Bar or Dot or Step charts	Lines focus on the overall pattern Bars focus on individual values Dots - best of both worlds Step - Useful for displaying how the levels in your data increase, remain constant or decrease over time
Ranking	Bar or in-cell or Sparklines Charts
Parts to a Whole	Bar or Column or Bullet charts Stacked Bars (occasionally)	Only use Pies if there are <= 3 items / segments
Deviation or Variance	Column or Bar or Line charts	When your target is a range, you can use a line or column chart compared to a range or tolerance
Distribution	Histogram	Box Plots (box and whisker chart) are another alternative but they're not as easily interpreted to the untrained user
Correlation	Scatter chart with a trend line

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A Word on Zero Axis

• A column or bar chart must always start at zero

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• A common accepted alternatives when starting the axis above zero is to use markers instead of columns

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Index