however , the complexity of ill - health , which is socially constructed by individuals , health personnel and health authorities have motivated the search for other forms to approach knowledge . to discuss the complementarities of qualitative and quantitative research methods in the generation of knowledge . the purpose of quantitative research is to measure the magnitude of an event , to make predictions , develop causal explanations . to achieve this it uses a pre - established design based on hypothesis and theories , conducts extensive data collection to a statistical sample and develops statistical data analysis . quantitative research objectives can be to establish the incidence or prevalence of a health problem ; the health personnel degree of adherence to a new intervention ; or , the users level of satisfaction with a service . its design is open , flexible and circular , data collection is intensive and based on a purposive sample and results will be achieved through inductive analysis . qualitative research allows to explore aspects thought as known , understands differences in personnel opinions and practice in front of new interventions or users opinion on services utilization . quantitative and qualitative methods are different research approaches , that not only provide complementary knowledge that contributes to gaining better understanding of a problem or situation , but that can be used in a combined way , to approach a new research area , to develop instruments and to interpret results .