Calambur R. Rao, often referred to as C.R. Rao, was a highly influential IndianAmerican mathematician and statistician whose groundbreaking work significantly shaped the field of statistics in the 20th century and continues to impact research today. Born in Karnataka, India, Rao received his early education in India before pursuing advanced studies at the University of Cambridge, where he earned his Ph.D. in 1948. His doctoral research focused on statistical inference and estimation theory, laying the foundation for many of his later contributions.

Rao's academic career spanned several prestigious institutions. He held positions at the Indian Statistical Institute, where he made substantial contributions to the development of statistical methods for national planning and development. He later moved to the United States, holding professorships at the University of Pittsburgh and Pennsylvania State University. His research interests were exceptionally broad, encompassing areas such as multivariate analysis, statistical inference, design of experiments, and applications of statistics to various fields, including genetics, anthropology, and medicine.

Among his most notable contributions are the CramerRao inequality, which establishes a lower bound on the variance of unbiased estimators, and the RaoBlackwell theorem, which provides a method for improving estimators. These theorems are fundamental concepts taught in virtually every graduatelevel statistics course. He also developed the concept of orthogonal arrays, which are widely used in experimental design and quality control. Rao's work was characterized by its mathematical rigor, practical relevance, and profound impact on the development of statistical theory and methodology. His contributions have been recognized with numerous awards and honors, solidifying his legacy as one of the most influential statisticians of all time.