Discussion - The process of how we study science

Discussion.  

The process of how we study science is the same for all disciplines, including Human Biology. In your opinion, which step of the scientific method is most important? In your discussion, define and describe this step.

In addition, research and find an example of a scientific discovery or observation related to human biology or human health (recent or in the past) that you believe misses this step of the scientific method. What effect does this have on the validity of the discovery or observation? Use and cite outside sources.