title: Problems and hypotheses.
abstract: The formulation and relationship of precisely defined research questions and hypotheses and their importance in the research process are discussed. A hypothesis is defined as a linkage of two or more abstract variables, each of which is derived from the observational level. The successive abstractions of the derivation process, the characteristics of the variables so derived, and the relationship of both to study design and measurement are defined and discussed.
mesh_terms: D000043:Abstracting and Indexing; D006801:Humans; D008606:Mental Processes; D008962:Models, Theoretical; D012107:Research Design; D013598:Systems Theory