Final answer:
The research method that requires multiple studies over an extended period to yield conclusive knowledge is known as longitudinal research.
Step-by-step explanation:
Creating a need for multiple studies over multiple years before conclusive knowledge is yielded refers to longitudinal research. This research strategy involves following a group of research participants for an extended period of time. Such studies require a significant time investment and often also a substantial financial investment due to the duration, which could span years or even decades. By repeatedly collecting data at different points in time, researchers can gain insights into how people or circumstances change and develop over time. Longitudinal Research has proven to be incredibly helpful in fields like human development and lifespan studies.