Automated Readability Index

Book excerpt: "Inasmuch as the utility of technical manuals is influenced to a marked extent by their reading difficulty or readability, the Automated Readability Index was devised to provide an easy, automated method of collecting data from which textual material can be evaluated in terms of readability. Whereas most readability formulas include separate factors related to (1) word difficulty and (2) sentence difficulty, the Automated Readability Index provides for the mechanical tabulation of the required data on passages as they are typed on a standard typewriter. Impulses from the typewriter activate counters which record the number of letters, words and sentences contained in the passage. From this, the average word length and average sentence length are computed. Appropriate weightings of these factors result in an index reflecting the readability of the passage. This index is in close agreement with other indexes of readability."--Abstract.