Automated readability index.

TLDR

Reading difficulty strongly influences the utility of technical manuals, motivating the development of the Automated Readability Index. The study aims to provide an easy, automated method for evaluating textual material’s readability. The index is computed mechanically by a typewriter that counts letters, words, and sentences, then calculates average word and sentence lengths and applies weightings to produce a readability score. The Automated Readability Index closely agrees with other readability indices.

Abstract

Abstract : 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 formulae 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 indices of readability.