A clearly defined question or problem is the starting point for an effective literature search. This step of the EIPH process helps you answer the question:
“Where should I look to find the best available research evidence to address the issue?”
Your search strategy should aim to locate the strongest quality and most relevant evidence first. When searching for quantitative evidence (e.g., effectiveness of an intervention, health effects, cost effectiveness, etc.) some study designs are considered stronger than others. It is important that the research design is the most appropriate to answer the question being asked.