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.
Are used whenever control of certain variables is possible and desirable. You wouldn't want to do a design experiment having people smoke cigs. That is why Observational Studies are necessary. They also have lower cost, greater timeliness, and broader range of patients.