This volume provides a comprehensive introduction to the principles and practices of experimental design, a cornerstone of empirical research across disciplines. Covering foundational topics such as sampling, randomization, and analysis of variance, alongside more advanced methods like factorial designs and multivariate approaches, this volume equips readers to design rigorous experiments with confidence. Whether you're preparing for exams, conducting field studies, or planning business trials, this book offers practical guidance through real-world examples--ranging from A/B testing in digital marketing to policy evaluations in the public sector. Designed for students, researchers, and practitioners alike, it emphasizes not only the technical aspects of design and analysis, but also the interpretation of results for decision-making. Readers will gain the skills to produce credible causal evidence and translate findings into actionable insights.