Whilst the greatest effort has been made to ensure the quality of this text, due to the historical nature of this content, in some rare cases there may be minor issues with legibility. Nearly all the material here presented has been ao cumulated from experience in the statistical laboratory and class-room. Particular attention has been given to the requirements in respect to fundamental theory of the statistical departments of the larger banks and business houses. Some of the recently developed methods of handling business barometers have there fore been touched upon, and some attention has been given to the theory of price and production indexes.