To accurately count survey invitations that have been started but not yet submitted, which visual should a report writer use in Power BI?

Using a card visual filtered by invitation status is the most effective way to accurately count survey invitations that have been started but not yet submitted. A card visual is specifically designed to display a single valuable metric in a concise format. By applying a filter to this visual, the report writer can isolate and showcase only those invitations that are in the "started" status, providing a clear count that meets the requirements of the question.

Other visuals, such as charts or tables, serve different purposes. Charts can display trends over time or comparative metrics but may not provide the focused, single-number insight that a card visual offers. A table lists all data entries but could overwhelm with information rather than highlight the key metric of interest. The donut chart, while useful for displaying proportions of different categories, does not specifically cater to the requirement of counting started but unsubmitted invitations, making it less effective in this context.