An Introduction to the Theory of Statistics is one of the most influential and enduring textbooks in the field of statistical science. Written by G. Udny Yule a pioneer of modern statistics the book provides a systematic and rigorous introduction to the principles methods and applications of statistical analysis. First published in 1911 it became a standard reference for students researchers and professionals and went through numerous revised editions later with contributions by M. G. Kendall. The book introduces readers to the fundamental concepts of statistical reasoning including the collection and classification of data measures of central tendency and dispersion probability frequency distributions correlation regression sampling theory index numbers and the theory of attributes. It emphasizes the mathematical foundations of statistics while illustrating their practical application through carefully selected examples drawn from the social sciences economics biology and public health.