Summary
To effectively show headcount growth patterns by department over the last six quarters for executive reporting, the most effective Workday approach involves using a Trending custom report with the "Trended Workers" data source. This allows you to display headcount numbers by department at the start and end of a period, with separate columns for each. For growth percentage calculations, you can create calculated fields to compare current and prior year headcounts.
For dynamic quarterly reporting, especially within a composite report, you can leverage the delivered 'Current Period YTD' time period and create a 'Lookup Date Rollup' calculated field. This field can then be used in your Matrix report with a repeating column group to group headcount by fiscal quarter or month and then by cost center. If your sub-reports are also trended worker reports, the 'Lookup Date Rollup' calculated field needs to be present in each sub-report for proper data distribution. Workday also provides delivered reports like "Headcount and FTE by Month" based on "Trended Workers" that are set up for calendar year and month trending, which can be a starting point for custom reports.
Retrieved From Workday Documentation
From Customers
- Headcount Growth Reporting by Department
- A Trending custom report can be useful for showing department growth compared to overall headcount growth

1.1.
- To show headcount numbers by department at the start and end of a period, a Trending custom report using the "Trended Workers" Data Source can be used

2.1. This allows for two headcounts for the start and end dates in separate columns 
2.1.
- For a growth percentage calculation, you can call the report for the current year, create a calculated field to return the headcount of the prior year, and another calculated field for the growth percentage

2.4.
- If you need to show headcount by month in a stacked bar chart for all workers, including contingent workers and employees, using "Trended Workers" and calendar month trending is suggested

3, 
3.1, 
3.2.
- Workday provides delivered reports for the "Trended Workers" business object, such as "Headcount and FTE by Month," which are set up for calendar year and month trending

3.2.1. You can then create custom reports off the "Trended Workers" data source 
3.2.1.
- To show quarter periods dynamically on a composite report, you can use the delivered 'Current Period YTD' time period within your Composite Report and change your Accounting Date to be a Summary Period by creating a 'Lookup Date Rollup' calculated field

4.3. This field can then be added to your Matrix report with a repeating column group 
4.3.
- For composite headcount reports grouped by fiscal quarter or month and then cost center numbers within that time period, you can create a Lookup Date Value calculated field within your sub-reports

5.6. This calculated field should be created as a "global" calc field so it can be used across multiple reports 
5.6. Then, define a repeating column group on your data column using this calculated field 
5.6.
- If your headcount sub-report is a trended worker report and requires grouping by a time period field, the same type of calculated field (Lookup Date Rollup) will need to exist in each of your sub-reports for the Composite report to distribute the data correctly

5.9.
- If you are not using the "Trended Workers" data source, you would have to run the report multiple times with a different report effective date for each month and then consolidate the output

3.2.1.1.