The causal analysis of qualitative data poses serious problems that the qualitative researcher has become immersed in the setting and may well adopt the perspective of the key informants.
At the same time, the researcher must retain an outsider’s skepticism in interpreting data. In practice, the analyst must switch back and forth between these perspectives, checking for consistencies and inconsistencies among the various informants and observations. In this final section, we will review qualitative methodology from the standpoint of each of the four main types of validity, construct, internal, statistical inference, and external.