A Matrix report summarizes instances into row groups and optional column groups. Select a grouping field and at least one measure, then choose the aggregation that answers the question. Count of Worker measures people; sum of FTE measures capacity. A count of nonblank manager IDs answers a different question again.
Keep the population visible in the report's name and definition. A matrix built from Workers for HCM Reporting with All Active Workers describes the current tenant population, while a termination summary needs All Workers with a dated exit filter. Blank group values can expose unresolved manager relationships. Don't hide them merely to make the output tidy. When column grouping splits a measure by worker type, reconcile the cells back to the same row population.