We'll be brainstorming how to reduce the "zero results" rate. We're probably going to think of lots of really good, interesting ideas, but we're shooting in the dark unless we have some insight into the queries that are currently yielding no results.
For this task, let's analyze the current data (i.e. what we used to come up with the 25% figure), and see what we can learn about queries that are failing to come up with results.
Stakeholder: The users who are currently failing to get search results
Benefit: Frame the team's planning for the next quarter
Estimate: Needs to be done before the brainstorming meeting