ABSTRACT
Research designs broadly fall into two groups of descriptive (or observational) and analytical (or experimental) studies and may involve individuals or populations. Which of these research designs is used depends upon the objectives and hypotheses to be tested. Traditionally, researchers define ‘exposure’ and ‘outcome’ measures, where exposure refers to the factors to which a person, or group of people, comes into contact (Margetts and Nelson 1998), while outcome measures refer to factors which are being studied in relation to the effects of an exposure. From a statistical/analytical point of view, exposures are the independent variables while outcomes are the dependent variables.
