Readability Revisited: The New Dale-Chall Readability Formula
Jeanne S. Chall, Harvard University, and Edgar Dale, Ohio State University
ISBN 1-57129-008-7, 1995, paper $29.95
Seven decades after the concept was first defined, readability is still a hotly debated topic. The Dale-Chall Readability Formula has been the most widely used and consistently valid method for estimating the difficulty of reading materials, particularly of textbooks and other educational materials, since it was published in 1948.
In Readability Revisited, Professors Chall and Dale present an introduction and historical overview of the original formula, its purposes and uses over the years and its relation to other measures of readability. The second chapter presents the new revised formula using a new set of criterion passages, an updated word list, and better rules for measuring the two factors of word familiarity and sentence length. The authors have also simplified the instructions and computations required to apply the formula. The assessment of readability combines this revised formula with measures based on the cognitive and structural elements of the written material, the characteristics of the target readers and the reading purpose. The combination provides a new and powerful tool for assessing and creating written materials for use by teachers, publishers, editors and writers.
Chapter 3 talks directly to issues of interpretation. Section 2 concerns standardization and validity of the new formula and demonstrates that the new formula predicts difficulty at a high level of accuracy. Section 3 discusses the various paradigms of readability measurement.
Readability Revisited offers a measured, thorough review of the history of the concept as it could only be presented by someone who has been a major figure in the field almost since its inception. Readability Revisited will remain both a standard reference and a definitive history for years to come.