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In this article

1. Apply a Reference in a Nested Analysis
   • Default Reference
   • Change the Reference
   • Set the Reference across Groups
   • Time Axes in Nested Analyses
   • Remove the Reference

1. Apply a Reference in a Nested Analysis

Significance testing allows us to compare data to a reference point. Being able to apply a grouped reference within an nested analysis allows you to compare individual items within the same group or compare those items across different groups.

• Default Reference: When you apply SIG testing to a nested table, the default setting compares the items in the lowest level of the nested group to the Total column.
• Change the Reference: Just as you can in a standard analysis, you can select a column within a nested group and set it as a reference. Select a column from the lowest level of the nest and click REF. Differences are compared within the nested group.
• Set the Reference Across Groups: Select a group from the second level of the nest and set the reference to compare differences with the same items across different groups. You can select a group from any level in the nested analysis to compare across groups.

🔗 Learn more about Statistical Significance in Harmoni (SIG)

Default Reference

When you turn on SIG in a nested analysis, the default reference is the total. In a nested analysis, the totals are turned off in the nested dimension. Use the Selector to display them if required. You can see the reference in the information bar.

• The default reference for SIG testing is the total column
• Drag in a new axis and nest into the across dimension at the bottom
• The reference is the total column (not visible)
• See the information bar to view the reference
• Use the Selector to add the totals
• Selecting the total confirms it is the reference (REF in orange)

Change the Reference

If you change the reference and then nest in a new axis as the outer level of the nest, the reference remains unchanged. If you nest in a new axis as the inner level, the reference returns to the default setting - Total (qualified).

Nest into the Outer Level:

• In a crosstab, select a column and change the reference by clicking REF
• Nest an axis as the outer level (in this example, at the Top)
• The reference remains unchanged as indicated in the i-bar
• Select the reference column and click REF to remove the reference

Nest into the Inner Level:

• In a crosstab, select a column and change the reference by clicking REF
• Nest an axis as the inner level (in this example, at the Bottom)
• Reference resets to default as seen in the i-bar
• Use the Selector to view totals - REF is indicated by the blue font
   

Set the Reference across Groups

You can select a group from any level of the nested analysis and set the reference.

1. Select the group you want to compare by clicking the column header label and set as REF from the modify menu.
2. The same items across different groups are compared and the associated significant differences are displayed.

In the above GIF and tables below, the following references are set:

• Firstly, the reference is set on the nested group, Tour:
  Females who travelled in a Package group or Independently are compared to females who travelled in a Tour group.
• Another level is nested into the analysis. The reference does not change, but the comparisons are now made within each Top 5 Markets:
  Females from Australia who travelled in a Package group or Independently are compared to females from Australia who travelled in a Tour group.
• Secondly, the reference is set on the first (top) level of the nest, in this case, Australia is selected. All other markets are compared to Australia, within each group:
  Female visitors from the UK who travelled in Tour groups are compared to female visitors from Australia who travelled in Tour groups. Each group is compared to the equivalent group from Australia.

In the example tables below, the same color highlighting identifies the items being compared, and the darker highlight of the same color identifies the reference in the group.

Reference is Tour

Reference is Australia

Time Axes in Nested Analyses

When you include a time axis in a nested analysis, for Harmoni to display a rolling reference, the time axis must be the first level of the nest. If you move the time axis to the outer levels of the nest, you will not see a rolling reference.

In the example below, Quarter is nested second (under Gender) and so the rolling reference is available. Amongst males, Q2 2025 is compared to the previous quarter, Q1 2025,

With the time period in the outer nest layer, the reference reverts to Total. Here you can see that within Q1, females are significantly lower than the total, while males are higher.

Remove the Reference

If you have changed the reference in a nested analysis and want to return the reference to the total, include the totals in the analysis, then select the total and set it as the reference. 

To include totals, use the Totals ON/OFF toggle or add it using the Selector.

• Blue text indicates the current SIG test reference set
• Use the Selector to include totals in the analysis
• Set the total column as the reference
• Hide totals if needed; the i-bar displays the reference

Where to from here?

Learn more about Harmoni:

• Statistical Significance in Harmoni (SIG)
• Nest Items in an Analysis
• Multi-Reference Statistical Significance in Harmoni (M-SIG)