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      How to create a Vertical biaxial bar chart

      A Vertical biaxial bar chart displays two different bar series on the same X-axis. It’s designed to help compare two different measured quantities over time—each with its own independent Y-axis.

      When to use a Vertical biaxial bar chart

      This format is ideal when you need to:

      • Visualise two related metrics with different units or scales (e.g. number of participants vs average hours of engagement), using bars for both.

      • Compare absolute values side by side while maintaining separate Y-axes for clarity.

      • Provide a clear, direct comparison of how two distinct measures behave across the same categories or time intervals.

      How to build a Vertical biaxial bar chart

      Step 1: Select the Chart Type

      • In the Explore Data tool, go to the Build Your Chart step.

      • Under the Type tab, select Vertical biaxial bar.

      Note: The Vertical biaxial bar chart option will be unavailable if any of the following conditions are present:

      • "Measured quantity" is missing from the chart Legend
      • "Measured quantity" contains fewer than 2 Categories
      • There are multiple Variables in the chart Legend
      • There are multiple chart tables present
      • Chart tables include calc tables

      Step 2: Create Vertical biaxial bar charts

      • Navigate to the Chart tab.
      • Ensure only one chart table is toggled on (not a calculation table).
      • The Legend should contain only the Measured quantity variable.
      • Select which measured quantities to show for each Bar.
        • By default, the first two are selected.
        • You can manually update them and click Apply.

      Step 3: Configure Y-Axis

      Vertical biaxial bar charts use two Y-axes:

      • Left Y-axis for the left Bar.

      • Right Y-axis for the right Bar.

      To customise them:

      • Go to the Custom tab.
      • Set the Y-axis titles:
        • Vertical Axis Title → for left Bar chart.
        • Secondary Vertical Axis Title → for right Bar chart.

      • Set the value type for each axis individually:
        • Choose between Percentage or Decimal for each Y-axis.

      Here is an example of a Vertical biaxial bar chart:

      When you hover over the chart, a tooltip will appear showing both bar values for that X-axis category.