INSIGHTS AND PITFALLS - SELECTION BIAS IN QUALITATIVE RESEARCH

Qualitative analysts have received stern warnings that the validity of their studies may be undermined by selection bias. This article provi des an overview of this problem for qualitative researchers in the fie ld of international and comparative studies, focusing on selection bia s that may result from the deliberate selection of cases by the invest igator. Examples are drawn from studies of revolution, international d eterrence, the politics of inflation, international terms of trade, ec onomic growth, and industrial competitiveness. The article first explo res how insights about selection bias developed in quantitative resear ch can most productively be applied in qualitative studies. The discus sion considers why qualitative researchers need to be concerned about selection bias, even if they do not care about the generality of their findings, and it considers distinctive implications of this form of b ias for qualitative research, as in the problem of what is labeled ''c omplexification based on extreme cases.'' The article then considers p itfalls in recent discussions of selection bias in qualitative studies . These discussions at times get bogged down in disagreements and misu nderstandings over how the dependent variable is conceptualized and wh at the appropriate frame of comparison should be, issues that are cruc ial to the assessment of bias within a given study. At certain points it becomes clear that the real issue is not just selection bias, but a larger set of trade-offs among alternative analytic goals.