When applying significance testing in Harmoni, the default reference is the total and you can change the reference to any column in your analysis table. Once you add different levels of nesting to the table, you can also change the reference to compare across the different groups within your nested analysis.
In this article, we will look at how to change the reference (REF) as you add new levels in a nested analysis.
In this article
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 SIG in Harmoni.
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.
- Create a standard analysis
- 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 in the total column
Change the Reference
After creating a nested analysis, you can change the reference from the default setting by selecting another column and clicking REF.
In this example, the statistical testing remains within the nest group. Changing the REF to Female compares the Totals and Male columns to the Female column within each of the groups; Tour, Package and Independent.
By default, totals are hidden in nested tables. If you want to view the total, use the Selector or click the Totals ON/OFF button.
Set the Reference across Groups
You can select a group from any level of the nested analysis and set the reference.
- Select the group you want to compare by clicking the column header label and set as REF from the modify menu.
- 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
Removing the reference and returning it to the default setting is a simple process.
- Select the column or group and click on REF.
- The significant test reference reverts to total.
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)