From the PREFACE. IN the preparation of this book there has been a constant effort to present the subject to suit the point of view of the business man, the social worker, and the legislator. Mathematics have been entirely eliminated. Technical terms are used practically not at all. Since the readers whom it is most desired to reach are those who have never had any statistical training, consistent effort has been made to keep the whole book on such a plane that it may be found readable and useful by anyone dealing with the complex facts of business or government. Though written primarily for the non-technical man, it is hoped that this book may, nevertheless, prove convenient to the engineer, the biologist, and the statistician. A definite effort has been made to produce a work which can serve as a hand book for anyone who may have occasional charts to prepare for reports, for magazine illustration, or for advertising. Unfortunately, there are extremely few draftsmen who know how to plot a curve or prepare any kind of a chart from data presented to them in the form of tabulated figures. Most draftsmen can plot a curve if they are given the data and an example showing the general type of chart desired. The executive who desires a chart is usually too busy to stand by a draftsman and explain in detail just how the chart should be prepared as concerns those all important details of proportion, scale, width of line, etc. It is believed that the owner of this book will find it feasible to run through the various chapters and pages until he finds a chart most nearly like that which he desires to have made from his own data. A sample chart placed before any draftsman of average ability should give the draftsman practically all the instruction needed for the preparation of a similar chart from other data. Much careful labor has been expended in so arranging the book that a busy reader may get the gist of the matter by looking at the illustrations and reading only the titles and the sub-titles. The main title under each illustration is intended to show exactly what the chart represents, just as if it were used in some publication relating to the particular subject matter of the chart. The sub-titles relate to method and give criticism of each chart as a whole. Though the text gives much more detailed information concerning method than can possibly be put into any sub-titles, the reader who examines only the illustrations and the titles, without any reference to the text, will undoubtedly get a major portion of the vital material in the book. It is believed that an average reader may go through the illustrations and the titles in about one hour....