An administrator is asked to create a report to calculate the year-over—year changed in the dollar amount of a company’s opportunities. What…

To calculate year-over-year changes, a report needs to compare a summary value from one group (the current year) with the same summary value from a previous group (the prior year). The PREVGROUPVAL function is specifically designed for this purpose in custom summary formulas. It allows a formula to reference a summary value from a preceding report grouping, making it ideal for period-over-period comparisons like year-over-year, quarter-over-quarter, etc., when the report is grouped by that time period.

A. A row-level formula operates on a single record and cannot access summary data from other records or groups.
B. A joined report is for combining different report types. While possible to structure, it's not the direct or intended tool for this calculation.
C. The PARENTGROUPVAL function compares a value to a parent grouping (e.g., a month's total vs. the year's total), not a previous peer grouping.

1. Salesforce Help. (2024). Calculate Group-to-Group Changes in Reports with PREVGROUPVAL and PARENTGROUPVAL. "Use PREVGROUPVAL to compare one grouping to previous groupings." The documentation provides a direct example of calculating year-over-year sales differences.

2. Trailhead. (2024). Reports & Dashboards for Lightning Experience Module, Use Summary Formulas Unit. "To compare a summary value from one grouping to another, use the PREVGROUPVAL() function."