The observation over a period of time of people taking part in a An investigation of a healthcare problem. There are different types of studies used to answer research questions, for example randomised controlled trials or observational studies. to measure Outcomes are measures of health (for example quality of life, pain, blood sugar levels) that can be used to assess the effectiveness and safety of a treatment or other intervention (for example a drug, surgery, or exercise). In research, the outcomes considered most important are ‘primary outcomes’ and those considered less important are ‘secondary outcomes’. under investigation (for example, their symptoms).