The Flesch index: An easily programmable readability analysis algorithm
John R. Talburt · 1985
This paper is an exposition of an algorithm for text analysis that can be of value to writers and documentalists. The simplicity of this algorithm allows it to be easily programmed on most computer systems. The author has successfully implemented this test as a function within a text editing system written in RPG II. Included in this paper is a sample program written for the VAX 11/780 in PL/I. In 1949 Dr. Rudolph Flesch published a book titled "The Art of Readable Writing." In this book, he described a manual method of reading ease analysis. This method was to analyze text samples of about 100 words. Each sample is assigned a readability index based upon the average number of syllables per word and the average number of words per sentence. This Flesch Index is designed so that most scores range from 0 to 100. Only college graduages are supposdd to follow prose in the 0- 30 range. Scores of 50-60 are high-school level and 90- 100 should be readable by fourth graders. Though crude, since it is designed simply to reward short words and sentences, the index is useful. It gives a basic, objective idea of how hard prose is to wade through. This test has been used by some state insurance commissions to enforce the readability of policies. Flesch's algorithm was automated in the early 1970s by the Service Research Permission to copy without fee all or part of this material is granted provided that the copies are not made or distributed for direct commercial advantage, the ACM copyright notice and the title of the publication and its date appear, and notice is given that copying is by