Preface

“Is coffee a necessary condition for you?” Someone asked me this question after hearing that I had taken time away in Italy to focus on writing my book, and that I like Italy’s coffee culture. “No, it is not; it only helps.” Focus, time, perseverance, and several other things are true necessary conditions. Without any of them, the book would not exist.

And here it is! In the book I present the principles of Necessary Condition Analysis (NCA) and their application in empirical studies in research and practice. NCA is an approach that uses necessity causal logic to identify necessary conditions from data. The core idea is that a necessary condition must be present to make the outcome possible, and that its absence guarantees the absence of the outcome. Compensation is not possible.

My intention with this book is to help researchers, data analysts, practitioners, and others develop a deeper understanding of the NCA approach and apply it effectively and with high-quality standards. The book brings together the fundamentals of NCA and integrates the most recent methodological advancements and tools. It synthesizes ideas from my earlier publications that describe NCA at introductory levels (e.g., Dul, 2016b, 2020) as well as more advanced treatments (Dul, Van der Laan, et al., 2020; Dul, 2021, 2024a), while also introducing more background, new topics, and recent developments. From 2021 to 2026, a regularly updated online predecessor of this book was available (Dul, 2021), which is now archived and integrated into the present book.

The first chapter of this book provides a general introduction to the possibilities and current use of NCA. Next, Part I contains five chapters on the principles of NCA, covering NCA’s causality, theory, mathematics, statistics, and its credibility for identifying necessity from data. Part II has six chapters about the application of these principles in empirical studies discussing NCA’s hypothesis formulation, data collection, data analysis, reporting, and how to apply NCA in multimethod research and in practice. I finish the book with a summary and a personal reflection.

The book’s content expresses my current understanding and interpretation of NCA. NCA develops over time, just like other methodological approaches do. As NCA is applied more widely, new questions, topics, insights, and ideas will emerge. An online version of the book with updates and additional materials is available via the book-page: https://jandul.github.io/NCA/. For the physical version of the book see Dul (2027).

I hope this book serves those who wish to gain a comprehensive understanding of the principles of NCA and their application, both in academic research and practical contexts.

Enjoy discovering and applying NCA!
   
Leiden, March 2026

References

Dul, J. (2016b). Necessary Condition Analysis (NCA): Logic and methodology of “necessary but not sufficient” causality. Organizational Research Methods, 19(1), 10–52. https://doi.org/10.1177/1094428115584005

Dul, J. (2020). Conducting Necessary Condition Analysis. Sage. https://uk.sagepub.com/en-gb/eur/conducting-necessary-condition-analysis-for-business-and-management-students/book262898

Dul, J. (2021). Advances in Necessary Condition Analysis. online book. https://bookdown.org/ncabook/advanced_nca2/

Dul, J. (2024a). A different causal perspective with Necessary Condition Analysis. Journal of Business Research, 177, 114618. https://doi.org/10.1016/j.jbusres.2024.114618

Dul, J. (2027). Necessary Condition Analysis (NCA): Principles and Application. Chapman & Hall/CRC Press. https://www.routledge.com/Necessary-Condition-Analysis-NCA-Principles-and-Application/Dul/p/book/9781032554471

Dul, J., Van der Laan, E., & Kuik, R. (2020). A statistical significance test for Necessary Condition Analysis. Organizational Research Methods, 23(2), 385–395. https://doi.org/10.1177/1094428118795272