Qualitative Comparative Analysis (QCA) is an approach for systematic comparison of cases. It integrates qualitative and quantitative analysis of cases to understand how combinations of causes and conditions interact to affect outcomes of interest. It starts from the premise that it is actual cases, in all their complexity, that make up the reality that needs to be understood. In this way the method is explicitly avoids a focus on variables - isolated and abstracted from real settings -‘since it is not variables, but cases which are real.

QCA was developed explicitly to address complexity in social processes and programmes. It seeks to move beyond the perceived weaknesses of experimental methods for their neglect of interactions and context, and their inability to address the why and how questions - the answers to which are important for understanding and improving social interventions.

QCA supports analysis of complex cases in a way that preserves their integrity as actually existing wholes, embedded in real life contexts. At the same time, it facilitates comparison and generalisation across many cases to draw out key combinations or configurations of factors and characteristics that seem to make a difference – that are either sufficient or necessary to explain the pattern of outcomes observed.

QCA is a relatively new method, with roots in both complexity theory and critical realism, and its procedures and guidance remain quite technical and academic. It is included in these introductory resources as a method that shows great promise, and for its relevance for evaluation of complex multi-stakeholder processes.

Video Introduction to QCA

Caption: A video introduction to QCA(6 minutes) from Wendy Olsen who introduces QCA and some of the set-theory upon which it is based, with a number of illustrative examples. Credit: Wendy Olsen.

More Information

Presentation: What is Qualitative Comparative Analysis (QCA)? (18 slides)

Charles Ragin

A brief introduction by QCA originator Charles Ragin. It includes background on the method, a worked-through example and a bibliography and links (including to free QCA software).

Website: Qualitative Comparative Analysis – introduction on Better Evaluation

A clear, if technical, overview and links to a variety of papers and resources.

Paper: Between complexity and generalization: addressing evaluation challenges with QCA

Barbara Befani, Evaluation 19 (3) 269-283, 2013

This paper outlines the case for Qualitative Comparative Analysis as a useful method in case-based evaluations for its focus on theory development and explaining causality, and for it being stronger on generalisation of findings than other case study methods.

The paper clearly explains and introduces the main elements of the method with simple examples. It also discusses the distinctive understanding of causality underpinning the method (and handled by the method) – notably the recognition of multiple configurations of factors that can combine to produce outcomes, and the notion that there may be multiple paths to the same outcomes (equifinality).

Book: Pathways to change: evaluating development interventions with Qualitative Comparative Analysis (QCA) (242 pages)

Barbara Befani, 2016

This freely available book by Babara Befani provides a clear and comprehensive introduction to Qualitative Comparative Analysis, with a range of illustrative examples and an account of practical challenges and trade-offs to be considered when applying the method in evaluation of social programmes. A step-by-step guide takes the reader through the key moments of design, data gathering and analysis, as well as how to address bias in the method and conduct sensitivity analysis. Another section describes the value of using Venn diagrams to aid analysis and highlights the strengths and weakness of different software.

An introductory section positions QCA in relation to other more traditional research and evaluation methods and clearly outlines it’s distinctive case comparative approach, and ability to understand the complex ‘recipes’ of real world factors that may be necessary or sufficient in producing outcomes of interest. Later chapters describe how QCA can complement other complexity sensitive methods such as realist evaluation and process tracing

Book: Configurational Comparative Methods: Qualitative Comparative Analysis (QCA) and Related Techniques (240 pages)

Benoit Rihoux and Charles Ragin (eds) (2009). Thousand Oaks: SAGE Publications.

An introduction and overview of the QCA rationale and method, including it’s ‘crisp-set’ ‘multi-value’ and ‘fuzzy-set’ varieties. Includes summary boxes, glossary and practice examples. Provides a range of examples of practical application and responds to some critiques of the method.

Book Chapter: Qualitative Comparative Analysis (QCA) as an Approach (18 pages)

Berg-Schlosser and others (2009). Introductory Chapter in above book Configurational Comparative Methods.

Book: Sage Handbook of Case-based Methods (560 pages)

David Byrne and Charles Ragin (2013) London: Sage

Wide-ranging and comprehensive, this handbook includes range of chapters on different aspects of case-based methods, their methodological rationale, application and history, with several chapters focusing on QCA.

Paper/guide: Using Qualitative Comparative Analysis (QCA) to Study Patient-Centred Medical Homes: An introductory guide (42 pages)

Kelly Devers et al (2013)

Clear explanation of the rationale and basic steps involved in applying QCA. Works through a detailed example of evaluating patient-centred medical homes and provides a review of key issues, potential for wider applications, and links to relevant literature and available software to support QCA analysis.

Paper: An Introduction to Applied Data Analysis with Qualitative Comparative Analysis (QCA) (88 pages)

Nicolas Legewie (2013). Forum: Qualitative Social Research, 14(3), Art. 

Technical introduction to the key elements of QCA and how they can practically be applied in social science research and analysis.

Website: COMPASS website and network on case comparative methods

COMPASSS (Comparative Methods for Systematic Cross-Case Analysis) is a worldwide network bringing together scholars and practitioners who share a common interest in theoretical, methodological and practical advancements in a systematic comparative case approach to research. It includes an extensive annotated bibliography, newsletter and details of events and training.

Paper: Variations between Spearhead areas in progress with tackling health inequalities in England (24 pages)

Tim Blackman, David Byrne, and Jonathan Wistow (2010) Durham: Durham University Wolfson Research Institute.

Accessible account of applying QCA to study of health inequalities across socially deprived boroughs in the UK, to understand how social programmes interacted with the existing context and resources in different boroughs to produce a variety of different outcomes for cancer, cardio-vascular disease and teenage pregnancy. Application of QCA helped to identify a number of different pathways for narrowing health inequalities to guide responsive strategic programming at the local level.

Paper: Using Qualitative Comparative Analysis to understand complex policy problems (16 pages)

Tim Blackman, Joanathan Wistow and David Byne (2013) Evaluation 19: 126-140.  

Journal paper covering the same study as the paper above on changes in health inequalities in socially deprived boroughs in the UK, with more detail and more academic references.

More resources on Qualitative Comparative Analysis can be found in the Mesh Qualitative Comparative Analysis resources category. To see how this resource fits in with the rest of Mesh's evaluation resources, and to learn how to navigate them, visit the Mesh evaluation page

This resource was developed by Robin Vincent as part of supporting the Wellcome Trust linked community of practice on evaluation of public and community engagement and was originally hosted on the eMOPs website.

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