Sir William Elderton's Frequency Curves and Correlation was originally published in 1906. It has remained a widely used book for upwards of sixty years, and has appeared in four editions. With each new edition the author took the opportunity to up-date the material in his book. With the passage of time, however, it became clear that further, and substantial, revision would be needed to include an adequate treatment of some more recent developments, and remove some material which was no longer of the same relative importance under present-day conditions.

The present work is the result of this revision of the fourth edition. The revision has been sufficiently drastic to warrant it being regarded as a new book, but much of the original material is still included, so that one might also consider it as a kind of ‘fifth edition’.

Although there are substantial changes from the fourth edition of Frequency Curves and Correlation, especial attention has been given to retaining the original character of the work. The new discussion of curves other than those in the Pearson system has been presented in a form as similar as possible to that in the earlier editions. Further, the level of treatment is as close as possible to that in the original work.

Practically all the material on correlation has been removed. This subject is now covered quite adequately in many textbooks. Of recent years it is the lucid description of Pearson system curves (in particular) which has underlain the continued popularity of Sir William Elderton's book.