9 sentences in accordance with their target reader level, the reader prior
knowledge and the author who is responsible in selecting the words and arranging them into sentences and who is aware of the real condition of their
reader or listener as their last target. Syntactic content and semantic structure author-based aspect that is related to their skill in selecting appropriate words
and sentences are as text-based aspect.
Measuring the readability of textbooks in terms of text aspect can use special software programs that have been computerized and can be
downloaded from the internet. The test is called readability test, readability formulas or readability matrices that work by counting syllables, words and
sentences. There are many popular readability formulas among other Coleman Liau index, Flesh Kincaid Grade Level, Automated Readability
Index ARI, SMOG
, Fry’s Readability Graph and many others.
D. Formulas of Readability
1. Classic Readability Formulas
There are many formulas of readability, according to Dubay they are divided into classic and new readability formulas. Since the earliest
of 1930s, many researchers have done their study in measuring the difficulties of texts or books. For instant, the research of adults reading
materials, Waples and Tyler have been done their research entitled What Adults Want to Read About, Ralph Ojemann under the title The Difficulty
of Adults Materials, Dale and Tyler entitled Adults of Limited Reading Ability, and Lyman Bryson Books for The Average Reader. In the 1931,
Patty and Painter did their research in measuring The Vocabulary Burden, and in 1935 Gray and Leary did their research entitled What
Makes a Book Readable. The formulations they used in measuring words, phrases or sentences are supposed as the beginning of the birth of
readability formulas.
6
Later on Dubay called them as classic readability formulas such as The Lorge Readability Index LRI, The Dale Chall
Readability Formula, and The Flesch Formulas. The Lorge Readability Index LRI is created by Irving Lorge
who is interesting in psychological studies of language and human learning. To him as quoted by Dubay that readability is based upon the
comprehension of passages by school children. The comprehension itself is judged by the correctness and completeness of responses to questions
about a passage. The questions commonly deal with specific details, general
import, appreciation,
knowledge of
vocabulary and
6
William H. Dubay, Ed. The Classic Readability Studies, Costa Mesa, CA: Impact Information. 2006, pp. 27
—28.
10 understanding of concept. The Lorge Readability Index was used to
predicting readability of passages.
7
The Dale Chall Readability Formula is created by Edgar Dale and Jeanne Chall. The Dale Chall formula uses a list of 3000 easy words.
The way using the formula is by counting the hard words outside the list. It spends much time, since it should be done manually; however, it is
easier in practice. As overviewed by Dubay, the formula is based on two counts; average sentence length and percentage of unfamiliar words
outside the Dale list of 3000 words. This formula is used for predicting readability.
8
The result of both counting are used to estimate corrected of grade level as shown in the table 2.1 below.
Table 2.1 Corrected Grade Level Estimation of Dale Chall Formula
Formula Scores Corrected Grade Level
4.9 and below 5.0 to 5.9
6.0 to 6.9 7.0 to 7.9
8.0 to 8.9 9.0 to 9.9
10 and above Grade 4 and below
Grades 5 – 6
Grades 7 – 8
Grades 9 – 10
Grades 11 – 12
Grades 13 – 15 college
Grades 16 and above college graduate
Source: The Classic Readability Studies
9
The Flesch formulas are published by Rudolf Flesch. As elaborated by Dubay he published two formulas, the first is readability
formula for measuring adults reading materials. The second formula consists of two parts, the first is Reading Ease formula which reduced
the use of affixes and used two variables they are the number of syllables and the number of sentences per 100 words sample. The second part of
this formula is predicting human interest by counting the number of personal words like pronouns and names, and personal sentences like
quotes, exclamations, and incomplete sentences.
10
The following is reading ease formula:
Score = 206.835 – 1.015 x ASL – 84.6 x ASW
Where: Score = position on a scale of 0 difficult to 100 easy ASL = average sentence length the number of words divided
by the number of sentences.
7
Ibid., pp. 44 —57.
8
Dubay. Op. Cit., pp. 61 —95.
9
Ibid. p. 71
10
Ibid. pp. 96 —97.
