Charles Chikwendu Okpala1 and Chukwudi Emeka Udu2
1 Professor: Industrial/Production Engineering Department, Nnamdi Azikiwe University, Awka, Nigeria.
2 Researcher: Industrial/Production Engineering Department, Nnamdi Azikiwe University, Awka, Nigeria.
Abstract
Despite its widespread adoption across manufacturing and service industries, Six Sigma has, over the years, continued to produce uneven implementation outcomes, which raises critical questions about the factors that truly drive its success in contemporary organizations. This study investigates the multidimensional determinants of successful Six Sigma implementation using a large, cross-industry dataset and a novel data-driven analytical approach. Drawing on insights from operations management, organizational behavior, data analytics, and sustainability science, the study integrates structural equation modeling with explainable machine learning to examine both causal relationships and nonlinear interaction effects. With the application of data from 412 organizations across multiple sectors and countries, the results reveal that leadership and strategic alignment, data and analytics maturity, human capital capability, and sustainability integration jointly explain a substantial proportion of variation in Six Sigma performance outcomes. Importantly, Six Sigma initiatives that explicitly incorporate sustainability objectives deliver significantly higher financial returns, stronger operational improvements, and measurable reductions in energy and material intensity when compared to traditional cost-focused projects. Methodologically, the study advances the Six Sigma literature through the demonstration of the value of the combination of causal and predictive analytics in the analysis of complex socio-technical systems. Substantively, it reframes Six Sigma as a strategic, data-driven mechanism for sustainable value creation, rather than a narrowly defined quality improvement tool. The findings offer actionable insights for managers, policymakers, and researchers who are aiming at aligning operational excellence with long-term sustainability goals.
Keywords: Six Sigma, Sustainability performance, Data-driven analytics, Operational excellence, Organizational capability, Explainable machine learning, Process improvement
References
- Aguh, P.S. and Okpala, C.C. (2025) ‘Learning in the age of artificial intelligence tutors: Cognitive outcomes and equity in automated education systems’, International Journal of Engineering Research and Development, 21(12), pp. 88–98. https://ijerd.com/paper/vol21-issue12/21128898.pdf
- Aguh, P.S., Udu, C.E., Chukwumuanya, E.O., et al. (2025) ‘Machine learning applications for production scheduling optimization’, Journal of Exploratory Dynamic Problems, 2(4), pp. 63-79. https://edp.web.id/index.php/edp/article/view/137
- Ajaefobi, J.O. and Okpala, C.C. (2026) ‘Six Sigma in the era of Industry 4.0: A bibliometric and benchmarking review’, International Journal of Engineering Research and Development, 22(3), pp. 71-84. https://www.ijerd.com/paper/vol22-issue3/22037184.pdf
- Antony, J. (2014) ‘Readiness factors for the Lean Six Sigma journey in the higher education sector’, International Journal of Productivity and Performance Management, 63(2), pp. 257-264. https://doi.org/10.1108/IJPPM-04-2013-0077
- Antony, J., Snee, R. and Hoerl, R. (2019) ‘Lean Six Sigma: Yesterday, today and tomorrow’, International Journal of Quality and Reliability Management, 36(2), pp. 199-211.
- Antony, J., Sony, M. and Gutierrez, L. (2017) ‘Can Lean Six Sigma make UK public sector organisations more efficient and effective?’, International Journal of Productivity and Performance Management, 66(7), pp. 995-1002.
- Argyris, C. and Schön, D.A. (1978) Organizational learning: A theory of action perspective. Addison-Wesley.
- Becker, G.S. (1964) Human capital: A theoretical and empirical analysis, with special reference to education. University of Chicago Press.
- Boudreau, M.C., Gefen, D. and Straub, D.W. (2003) ‘Validation in information systems research’, MIS Quarterly, 27(1), pp. 1-16.
- Cherrafi, A., Elfezazi, S., Govindan, K., et al. (2016) ‘A framework for the integration of Green and Lean Six Sigma for superior sustainability performance’, International Journal of Production Research, 54(15), pp. 4481-4510. https://doi.org/10.1080/00207543.2016.1164662
- Chukwunedum, O.C., Okpala, C.C. and Udu, C.E. (2026) ‘A data-driven integration of total productive maintenance and Industry 4.0 technologies: A machine learning framework for predictive OEE optimization’, International Journal of Engineering Research and Development, 22(3), pp. 85-95. https://www.ijerd.com/paper/vol22-issue3/22038595.pdf
- Coronado, R.B. and Antony, J. (2002) ‘Critical success factors for the successful implementation of Six Sigma projects in organisations’, The TQM Magazine, 14(2), pp. 92-99.
- Deswal, P. (2025) ‘Article 6 of the Paris Agreement: A comprehensive review of mechanisms, progress, and persistent challenges’, International Journal of Technology, Health and Sustainability, 1(2), pp. 111-125. https://ijths.com/wp-content/uploads/IJTHS-010235.pdf
- Deswal, S. and Deswal, P. (2025) ‘Sustainability: Greenhouse Gas Protocol and global GHG emissions’ status and trends’, International Journal of Multidisciplinary Research and Growth Evaluation, 6(1), 2051-2063. https://doi.org/10.54660/.IJMRGE.2025.6.1.2051-2063
- Deswal, S. and Pal, M. (2025) ‘Uncertainty estimation in predicting oxygenation by plunging jet aerators using probabilistic machine learning and conformal prediction’, International Journal of Technology, Health and Sustainability, 1(2), pp. 83-93. https://ijths.com/wp-content/uploads/2025/12/IJTHS-010230.pdf
- Elkington, J. (1997) Cannibals with forks: The triple bottom line of 21st century business. Capstone.
- Ezeanyim, O.C., Okpala, C.C. and Udu, C.E. (2026) ‘Artificial intelligence-enabled Lean Six Sigma: A multi-industry longitudinal analysis of operational performance and sustainable digital transformation’, International Journal of Technology, Health and Sustainability, 2(2), pp. 428-439. https://ijths.com/wp-content/uploads/IJTHS-0202001.pdf
- Garza-Reyes, J.A., Kumar, V., Chaikittisilp, S., et al. (2018) ‘The effect of lean methods and tools on the environmental performance of manufacturing organisations’, International Journal of Production Economics, 200, pp. 170-180.
- Goh, T.N., Low, P.C., Tsui, K.L., et al. (2006) ‘Impact of Six Sigma implementation on stock price performance’, Total Quality Management and Business Excellence, 17(6), pp. 791-802.
- Hair, J.F., Black, W.C., Babin, B.J., et al. (2019) Multivariate data analysis. 8th ed. Cengage.
- Hart, S.L. and Dowell, G. (2011) ‘A natural-resource-based view of the firm’, Journal of Management, 37(5), pp. 1464-1479.
- Henderson, J.C. and Venkatraman, N. (1993) ‘Strategic alignment: Leveraging information technology for transforming organizations’, IBM Systems Journal, 32(1), pp. 4-16.
- Igbokwe, N.C., Okpala, C.C. and Nwamekwe, C.O. (2024a) ‘The implementation of Internet of Things in the manufacturing industry: An appraisal’, International Journal of Engineering Research and Development, 20(7), pp. 510-516. https://www.ijerd.com/paper/vol20-issue7/2007510516.pdf
- Igbokwe, N.C., Okpala, C.C. and Nwankwo, C.O. (2024b) ‘Industry 4.0 implementation: A paradigm shift in manufacturing’, Journal of Inventive Engineering and Technology, 6(1), pp. 20-26. https://jiengtech.com/index.php/INDEX/article/view/113/135
- Laureani, A. and Antony, J. (2017) ‘Leadership characteristics for Lean Six Sigma’, Total Quality Management and Business Excellence, 28(3-4), pp. 405-426.
- Laureani, A. and Antony, J. (2019) ‘Some links between Lean Six Sigma and ISO 9001’, The TQM Journal, 31(2), pp. 161-173.
- Linderman, K., Schroeder, R.G., Zaheer, S., et al. (2003) ‘Six Sigma: A goal-theoretic perspective’, Journal of Operations Management, 21(2), pp. 193-203.
- Lundberg, S.M. and Lee, S.-I. (2017) ‘A unified approach to interpreting model predictions’. Advances in Neural Information Processing Systems 30, pp. 4765-4774.
- Ogbodo, I.F., Okpala, C.C. and Egwuagu, O.M. (2026) ‘From lean waste to measurable sustainability: Data-driven optimization in smart manufacturing’, International Journal of Technology, Health and Sustainability, 2(2), pp. 523-532. https://ijths.com/wp-content/uploads/IJTHS-0202020.pdf
- Okpala, C.C. (2026) ‘Machine learning-enabled design of composite materials: Scalable structure-processing-property relationships across applications’, International Journal of Technology, Health and Sustainability, 2(1), pp. 154-161. https://ijths.com/wp-content/uploads/IJTHS-020166.pdf
- Okpala, C.C. and Chukwumuanya, E.O. (2025) ‘The future of cybersecurity: Predictive analytics and machine learning applications’, Journal of Engineering Research and Applied Science, 14(2), pp. 190-201. https://www.journaleras.com/index.php/jeras/article/view/398
- Okpala, C.C., Nwamekwe, C.O. and Onukwuli, S.K. (2026) ‘Ergonomics in the age of Industry 5.0: A multilevel data analytics approach linking human-robot collaboration, cognitive load, and productivity in smart manufacturing systems’, International Journal of Engineering Research and Development, 22(3), pp. 59-70. https://www.ijerd.com/paper/vol22-issue3/22035970.pdf
- Okpala, S.C. and Okpala, C.C. (2026) ‘Six Sigma implementation success factors across manufacturing, healthcare, and services: A large-scale multidisciplinary analysis’, International Journal of Technology, Health and Sustainability, 2(1), pp. 311-321. https://ijths.com/wp-content/uploads/IJTHS-020189.pdf
- Onukwuli, S.K., Okpala, C.C. and Udu, C.E. (2026) ‘Sustainable nanocomposites: The integration of materials design, lifecycle performance, and data analytics’, International Journal of Technology, Health and Sustainability, 2(2), pp. 591-601. https://ijths.com/wp-content/uploads/IJTHS-0202029.pdf
- Podsakoff, P.M., MacKenzie, S.B., Lee, J.-Y., et al. (2003) ‘Common method biases in behavioral research: A critical review’, Journal of Applied Psychology, 88(5), pp. 879-903.
- Porter, M.E. and van der Linde, C. (1995) ‘Toward a new conception of the environment-competitiveness relationship’, Journal of Economic Perspectives, 9(4), pp. 97-118.
- Schroeder, R.G., Linderman, K., Liedtke, C., et al. (2008) ‘Six Sigma: Definition and underlying theory’, Journal of Operations Management, 26(4), pp. 536-554.
- Snee, R.D. (2010) ‘Lean Six Sigma—Getting better all the time’, International Journal of Lean Six Sigma, 1(1), pp. 9-29.
- Sony, M., Antony, J. and Douglas, J. A. (2020) ‘Essential ingredients for the implementation of Quality 4.0’, The TQM Journal, 32(4), pp. 779-793.
- Udu, C.E., Ejichukwu, E.O. and Okpala, C.C. (2025) ‘The application of digital tools for supply chain optimization’, International Journal of Multidisciplinary Research and Growth Evaluation, 6(3), pp. 308-316. https://www.allmultidisciplinaryjournal.com/uploads/archives/20250508172828_MGE-2025-3-047.1.pdf
- Udu, C.E. and Okpala, C.C. (2025) ‘Digital twin technology in water treatment: Real-time process optimization and environmental impact reduction’, International Journal of Engineering Inventions, 14(5), pp. 8-15. https://www.ijeijournal.com/papers/Vol14-Issue5/14050815.pdf
- Udu, C.E. and Okpala, C.C. (2026) ‘Artificial intelligence-enabled resilient scheduling: A systematic review and research roadmap for digital twin and machine learning in disruption-aware operations’, International Journal of Technology, Health and Sustainability, 2(2), pp. 486-497. https://ijths.com/wp-content/uploads/IJTHS-0202014.pdf
- Waller, M. A. and Fawcett, S. E. (2013) ‘Data science, predictive analytics, and big data: A revolution that will transform supply chain design and management’, Journal of Business Logistics, 34(2), pp. 77-84.
- Zu, X., Fredendall, L. D. and Douglas, T. J. (2008) ‘The evolving theory of quality management: The role of Six Sigma’, Journal of Operations Management, 26(5), pp. 630-650.
