Brachial Plexus Injuries. The brachial plexus is a network of intertwined nerves that control movement and sensation in the arm and hand. A traumatic brachial plexus injury involves sudden damage to these nerves, and may cause weakness, loss of feeling, or loss of movement in the shoulder, arm, or hand.
There are three main types of descriptive methods: observational methods, case-study methods and survey methods. This article will briefly describe each of these methods, their advantages, and their drawbacks.
Research Study Types. There are many different types of research studies, and each has distinct strengths and weaknesses. In general, randomized trials and cohort studies provide the best information when looking at the link between a certain factor (like diet) and a health outcome (like heart disease). Laboratory and Animal Studies.