be helpful in answering all three types of questions; Table 5-6 provides examples illustrating how this type of evidence can address “What” and “How” questions.

Limitations of qualitative methods lie in the subjectivity they introduce by making the researcher an instrument of the research process and the difficulty of bringing closure to open-ended forms of inquiry. There are well-developed conventions for adding rigor to qualitative inquiry, such as triangulation, convergent validation, and internal and external criticism (see Chapter 6).

Mixed-Method Studies

Mixed-method studies employ methodologies drawn from a variety of disciplines, including both qualitative and quantitative data gathering and analysis methods. Studies may combine extensive descriptions of context and the experiences of program participants with standardized assessments of changes in institutional, environmental, or individual behavior–related variables. The realization that these types of data are complementary has increased interest in the use of such studies in the public health arena. Examples of mixed-method studies include surveys and interviews combined with RCTs, interviews combined with interrupted time series analysis, policy-related content analysis combined with focus group interviews, health impact analysis using archival databases and surveys, economic analysis using archival databases and surveys, systems mapping based on a review of the literature, simulation studies, and mixed-method evidence synthesis techniques (discussed in the next section). Roux and colleagues (2008) use a combination of a systematic review of disease burden and data from clinical trials, population-based surveys, and other published literature to assess the cost-effectiveness of community-based physical activity interventions associated with disease incidence. This type of research is particularly helpful in answering “What” questions. Mixed-method studies may also help in garnering evidence to

TABLE 5-6 Types of Qualitative Evidence and Examples of Their Uses

Type of Evidence

Questions That Can Be Addressed

Specific Applications

Logic Modeling or Program Theory Analysis

What are the underlying assumptions about how an intervention will improve health outcomes? What are the expected causal pathways? What intervening factors in the larger system and community are likely to affect outcomes? (“What” questions)

A content analysis and systematic review of documents and literature relevant to an intervention to develop a logic model or causal path diagram

Process Delivery and Implementation Monitoring

What features of program implementation are associated with the maximum effect of this program? (“What” question)

What are the documented barriers to implementation of this intervention, and how have they been overcome? (“How” question)

A qualitative focus group interview of program delivery personnel from an effective program

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