This essay has as its objective to present the different existing conceptions on validity and on the various ways to assess it, discussing these issues within the scope of qualitative research. The methodology employs the comparative analysis. It was observed that the conceptions of validity can be grouped in three major blocks: conceptions related to the stage of formulation of the study (prior validity), conceptions related to the stage of development of the research (internal validity), and conceptions related to this stage of the results of the study (external validity). It could be noted in each of these stages the presence both of authors with a quantitative perspective and of those with a qualitative view, although their approaches are distinct. The conceptions of validity close to the positivist origins are more concerned with the validity in the formulation and in the results, whereas the more interpretivist conceptions of validity give more emphasis to the development of the research, without, however, disregarding the concern with formulation and results. It can be concluded that a qualitative researcher can and should concern him/herself with the validity of the three stages of the study: formulation, development and results. The validity in qualitative studies seems, therefore, to be wider and more detailed, albeit less quantitatively measurable.
Qualitative research; Validity; Reliability
