Why do hunters need to complete a survey even if they didn't shoot a deer?

Knowing if a hunter did not shoot a deer is just as valuable as knowing if they did. In fact, it is sometimes more desirable to know when and where hunters were unsuccessful, because this may suggest lower deer populations in those units. Moreover, there is other valuable information about hunting activity in addition to success, such as participation and effort. Participation data is used to estimate harvest for unsampled hunters, and effort data is used to compare harvest relatively across different hunting units and past years (i.e. total deer harvested per total days of hunting).