2. Put a suet feeder out in winter. In the winter use a suet feeder to provide extra energy for cardinals and other birds. While this will probably not be the primary feeding choice of cardinals in your area, they may come to a suet feeder to find extra food in the winter.. Put a suet feeder out in winter. In the winter use a suet feeder to provide extra energy for cardinals and other birds. While this will probably not be the primary feeding choice of cardinals in your area, they may come to a suet feeder to find extra food in the winter.
A pilot experiment/study is often used to test the design of the full-scale experiment which then can be adjusted. It is a potentially valuable insight and should anything be missing in the pilot study it can be added to the full-scale (and more expensive) experiment to improve the chances of a clear outcome.
Case control studies are observational because no intervention is attempted and no attempt is made to alter the course of the disease. The goal is to retrospectively determine the exposure to the risk factor of interest from each of the two groups of individuals: cases and controls. These studies are designed to estimate odds. Case control studies are also known as retrospective studies and case-referent studies..