In a cohort study, why might you want to start by selecting a defined population for study, rather than starting by selecting exposed and non-exposed individuals?

Sam and ben have discovered some strange animals living in the woods behind their house. ben is excited because he believes they are marsupials, an animal he's never observed in the wild before. his brother is sure it is not. what feature should the boys consider in deciding whether the animals are marsupials?

1. what is the electoral college? 




Lyle is concerned about the difference between a company's salaries for its white workers and its colombian workers. in order to place economic pressure on the company, what does lyle need to do?