These institutions have areas of specialism they particularly focus on, and research conducted by those sociologists will focus on expanding knowledge in that area of society
Large scale responses are more likely to use quantitative methods like closed questionnaires and structured interviews
Participants are vulnerable e.g. gangs, victims of domestic violence, so researcher is unlikely to use questionnaires and more likely to use unstructured interviews or observation for hard to reach groups
Not all sociologists are easy to identify as a functionalist, Marxist etc. Not all conflict theorists follow the teachings of Marx, some are influenced by Weber