Paramount to understanding the three approaches to research it is important to understand that the real divide is centered on the way in which each paradigm and its advocates view the world in terms of different “ontological, epistemological and axiological assumptions” (Onwuegbuzie & Leech, 2005, p.268). Quantitative research is founded on positivism wherein science prevails and belief is on there is only one singular reality or truth (Cresswell, 1998. Sale, Lohfeld & Brazil, 2002) that can be assessed with validity and reliability. whereas qualitative research is founded on constructivism and interpretivism (Sale et al, 2002) wherein behavior prevails and belief is on multiple realities or truths that are formed by societies, are dynamic (Sale et al, 2002) and thus assessment is open to interpretation.
Epistemological differences are to do with the relationship between the researcher and the researched or study objectives (Onwuegbuzie & Leech, 2005). positivists believe the two are separate and objective and that the researcher is capable of undertaking a study without affecting or manipulating the results. whereas interpretivists and constructivists take the opposite view that both are dependent on each other and so findings or results are founded from the perspective of both the researcher and the researched (Sale et al, 2002).
Axiological assumptions are to do with research values and while positivists purport that because epistemologically the researcher is independent of the study the research is value-free. interpretivism and constructivists, however, believe that because the researcher is not isolated from the study their values significantly impact on the research (Sale et al, 2002).
Apart from distinguishing one research approach from another by the underlying paradigm, philosophical or world outlooks they can also be differentiated and thus defined by the logic and the kind of investigation and data used, together with the way data is analyzed and explained (Bazeley, 2004).