Practical strategies for combining qualitative and quantitative methods: applications to health research.

This article describes a series of research designs for combining qualitative and quantitative methods, using a Priority-Sequence Model that relies on the principle of complementarity. First, a decision about the priority of the two methods selects either a qualitative or a quantitative approach to be the principal method. Second, a decision about sequencing determines whether the complementary method will serve as either a preliminary or a follow-up to the principal method. These two decisions yield four basic research designs: (a) preliminary qualitative methods in a quantitative study, (b) preliminary quantitative methods in a qualitative study, (c) follow-up qualitative methods in a quantitative study, and (d) follow-up quantitative methods in a qualitative study. The conclusions consider further research designs and the expertise necessary for multiple-methods research.