Positivism is the application of scientific method to sociology. Sociologists grouped sociology in with other natural sciences, such as physics and chemistry; they looked for facts, not opinion, tradition or revelation. Positivists believe in the theory of cause and effect, and believe society and societal conditions dictates behavior, such as a recession causing higher crime rates, not free will. Positivists distinguish between theories and what they observe. The only facts are those that can be directly observed. Here, knowledge is based on experience only. Research is done through structured interviews, surveys, experiments and observations.
Interpretivism criticizes positivism, but still considers logic and scientific method for evaluating society; however, they consider natural and social sciences differently, and create separate evaluation methods. Interpretivism believes individuals purposely choose actions and they apply their own meaning to those actions. Society does not make people act in specific ways, but the people interpret social situations and choose their actions. For instance, instead of investigating the cause of crime, criminal behavior is interpreted from the criminal's viewpoint. Research is more lenient and includes unstructured interviews and participant observation.
Realism agrees with positivism that sociology can be evaluated through the scientific method. The difference is that not all evidence is strictly observed. Realism understands the hidden aspects of individual and societal behaviors. Realism is driven by theory, not by observation, and there is no separation between theory and observation. Theories are created and data is gathered to support the theory. Data that supports the theory is always collected and theories are not tested against one another.
Interdependence illustrates and explores the relationship between an individual's immediate "world" and society as a whole. Interdependence evaluates the connection between these two types of actions; however, there is no "society as a whole." Each individual society, group and country is very different from others, so actions and reactions are not uniform across groups. Government, educational systems and the economy all depend on each other and individuals depend on all three.