A non-randomised 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. is any quantitative study estimating the The ability of an intervention (for example a drug, surgery, or exercise) to produce a desired effect, such as reduce symptoms. of an A treatment, procedure or programme of health care that has the potential to change the course of events of a healthcare condition. Examples include a drug, surgery, exercise or counselling. (harm or benefit) that does not use Randomization is the process of randomly dividing into groups the people taking part in a trial. One group (the intervention group) will be given the intervention being tested (for example a drug, surgery, or exercise) and compared with a group which does not receive the intervention (the control group). to allocate people to comparison groups.