I provide: * Known tasks and how long each will take (with error bars), * An overview of known unknowns, how they might impact the project, and what research

I provide: * Known tasks and how long each will take (with error bars), * An overview of known unknowns, how they might impact the project, and what research would bring them into focus, * Then I bring up the dreaded unknown unknowns. With reasonable leadership that usually leads to good discussions about reining in the scope.