definitive experiments are rare in the fields of science and medicine
instead, conclusion generally emerge from integration and synthesis of evidence from a variety of sources
using a similar approach, lawyers argue cases in which each piece of evidence is considered circumstantial in the hope that eventually the circumstantial evidence will become overwhelming
like lawyers, scientific researchers gather and regather circumstantial evidence from several perspectives with the goal of understanding cause and effect
by studying the relationships among variables and investigating mechanisms, they are able to from perspectives that are robust and plausible
this type of research work, together with longitudinal studies, tests the causative factors identified in the mechanistic studies