Hypotheses must be stated unequivocally, since the researcher's task is to prove (ratify, verify) or refute them, as this is an essential quality of any hypothesis (Bunge, 1989). It must be a probable solution, it has to be tried (del Río and Velázquez, 2005: 56). Hypotheses are "basic statements that are tested in research," a conjecture, an assumption or inference, "an assumption, an initial suspicion." It is also “an outline of sociological law; if the hypothesis is verified by experience it becomes law, and if it is otherwise abandoned, a new hypothesis is formulated which in turn will be investigated ” (Duverger, 1996: 385).

The hypotheses usually expose a relationship between two variables, although they could be more. The hypotheses "contain predictions about the relationships between the two variables." The variables that are present in the hypothesis will be those that the researcher uses to measure it. Variables must be defined conceptually and operationally