What does readability mean? How to measure it in mass communication?
INTRODUCTION
In 1998, traffic accidents caused 46 percent of all accidental deaths of infants and children aged 1 to 14 (National Center for Health Statistics, 2000). One study (Johnston et al. 1994) showed that the single strongest risk factor for injury in a traffic accident is the improper use of child-safety seats. Another study (Kahane 1986) showed that, when correctly used, child safety seats reduce the risk of fatal injury by 71 percent and hospitalization by 67 percent.
To be effective, however, the seats must be installed correctly. Other studies, showed that 79 to 94 percent of car seats are used improperly (National Highway Traffic Safety Administration 1996, Decina and Knoebel 1997, Lane et al. 2000).
Public-health specialists Dr. Mark Wegner and Deborah Girasek (2003) suspected that poor comprehension of the installation instructions might contribute to this problem. They looked into the readability of the instructions and published their findings in the medical journal Pediatrics. The story was covered widely in the media.
The authors referred to the National Adult Literacy Study (National Center for Educational Statistics, 1993), which states the average adult in the U.S. reads at the 7th grade level. They also cited experts in health literacy who recommend that materials for the public be written at the fifth or sixth-grade reading level (Doak et al., 1996; Weiss and Coyne, 1997).
Their study found that the average reading level of the 107 instructions they examined was the 10th grade, too difficult for 80 percent adult readers in the U.S. When texts exceed the reading ability of readers, they usually stop reading. The authors did not address the design, completeness, or the organization of the instructions. They did not say that the instructions were badly written. Armed with the SMOG readability formula, they found the instructions were written at the wrong grade level. You can be sure the manufacturers of the car safety seats are scrambling to re-write their instructions.
Guidelines for readability:
In works about technical communication, we are often told how to avoid such problems. For example, JoAnn Hackos and Dawn Stephens in Standards for Online Communication (1997) ask us to “conform to accepted style standards.” They explain:
Many experts, through much research, have compiled golden rules of documentation writing. These rules apply regardless of medium:
- Use short, simple, familiar words
- Avoid jargon.
- Use culture-and-gender-neutral language.
- Use correct grammar, punctuation, and spelling.
- Use simple sentences, active voice, and present tense.
- Begin instructions in the imperative mode by starting sentences with an action verb.
- Use simple graphic elements such as bulleted lists and numbered steps to make information visually accessible.
For more suggestions, we recommend referring to one of many excellent books on writing style, especially technical style.
We all know of technical publications that do not follow these guidelines and are read only by a small fraction of the potential readership. One reason may be that the writers are not familiar with the background and research of these guidelines.
This paper looks most carefully at two of the most important elements of communication, the reading skills of the audience and the readability of the text.
The readability formulas:
In the 1920s, educators discovered a way to use vocabulary difficulty and sentence length to predict the difficulty level of a text. They embedded this method in readability formulas, which have proven their worth in over 80 years of application.
Progress and research on the formulas was something of a secret until the 1950s. Writers like Rudolf Flesch, George Klare, Edgar Dale, and Jeanne Chall brought the formulas and the research supporting them to the marketplace. The formulas were widely used in journalism, research, health care, law, insurance, and industry. The U.S. military developed its own set of formulas for technical-training materials.
By the 1980s, there were 200 formulas and over a thousand studies published on the readability formulas attesting to their strong theoretical and statistical validity.
Are the readability formulas a problem?
In spite of the success of the readability formulas, they were always the center of controversy. When the “plain language” movement in the 1960s resulted in legislation requiring plain language in public and commercial documents a number of articles attacked the use of readability formulas. They had titles like, “Readability: A Postscript” (Manzo 1970), “Readability: Have we gone too far?” (Maxwell 1978), “Readability is a Four-letter Word” (Selzer 1981), “Why Readability Formulas Fail” (Bruce et al. 1981), “Readability Formulas: Second Looks, Second Thoughts” (Lange 1982), “Readability Formulas: What’s the Use?” (Duffy 1985) and “Last Rites for Readability Formulas in Technical Communication” (Connaster 1999).
Many of the critics were honestly concerned about the limitations of the formulas and some of them offered alternatives such as usability testing. Although the alternatives are useful and even necessary, they fail to do what the formulas do: provide an objective prediction of text difficulty.
Although the concerns of the formula critics have been amply addressed elsewhere (Chall 1984, Benson 1984-1985, Fry 1989b, Dale and Chall 1995, Klare 2000), we will examine them again in some detail, with a special regard for the needs of technical communication.
The purpose of this article is to very briefly review the landmark studies on readability and the controversy regarding the formulas. I will be happy if you learn something of the background of the formulas, what they are good for, and what they are not. That knowledge will give you greater confidence and method in tailoring your text for a specific audience.
What is readability?
Readability is what makes some texts easier to read than others. It is often confused with legibility, which concerns typeface and layout.
George Klare (1963) defines readability as “the ease of understanding or comprehension due to the style of writing.” This definition focuses on writing style as separate from issues such as content, coherence, and organization. In a similar manner, Gretchen Hargis and her colleagues at IBM (1998) state that readability, the “ease of reading words and sentences,” is an attribute of clarity.
The creator of the SMOG readability formula G. Harry McLaughlin (1969) defines readability as: “the degree to which a given class of people find certain reading matter compelling and comprehensible.” This definition stresses the interaction between the text and a class of readers of known characteristics such as reading skill, prior knowledge, and motivation.
Edgar Dale and Jeanne Chall’s (1949) definition may be the most comprehensive: “The sum total (including all the interactions) of all those elements within a given piece of printed material that affect the success a group of readers have with it. The success is the extent to which they understand it, read it at an optimal speed, and find it interesting.”
The classic readability formulas
Harry D. Kitson—Different readers, different styles Psychologist Harry D. Kitson (1921) published The Mind of the Buyer, in which he showed how and why readers of different magazines and newspapers differed from one another. Although he was not aware of Sherman’s work, he found that sentence length and word length measured in syllables are important measures of readability. Rudolph Flesch would incorporate both these variables in his Reading Ease formula 30 years later.
Although Kitson did not create a readability formula, he showed how his principles worked in analyzing two newspapers, the Chicago Evening Post and the Chicago American and two magazines, the Century and the American. He analyzed 5000 consecutive words and 8000 consecutive sentences in the four publications. His study showed that the average word and sentence length were shorter in the Chicago American newspaper than in the Post, and the American magazine’s style simpler than the Century’s, accounting for the differences in their readership.
The Flesch Formulas:
Flesch indicated that he was working on a new formula element that was the “percentage of nondeclarative.sentences,” and that this element correctly indicated that James was more readable than Koffka. Flesch did come out with a revised formula the following year, but it did not contain the “percentage of nondeclarative sentences.” Instead, Flesch (1948) had dropped the count of “personal references” from the readability formula and used it to create a new “human interest” formula. Another change was that the count of affixes in the readability formula had been replaced by a measure of word length, the number of syllables per 100 words. TJie results were two formulas, the reading ease formula and the human interest formula, both still in use today.
The reading ease formula is as follows:
R.E. = 206.835 – .846 wl – 1.015 si
where R.E. = reading ease score
wl = number of syllables per 100 words si = average number of words per sentence
The resulting score should range between 0 and 100 and can be looked up in a chart such as the one presented in Table 7.1.
The human interest formula is as follows:
H.I. = 3.635 pw + .314 ps
where H.I. = human interest score
pw = number of personal words per 100 words ps = number of personal sentences per 100 sentences
The resulting score should fall between 0 and 100 and can be looked up in a chart such as the one in Table 7.2.
The Flesch reading ease formula has proved to be the most widely used readability formula (Klare, 1963). Jt was popularized in a book published in 1949— The Art of Readable Writing.
The Flesch reading ease formula has produced a number of useful offshoots. The Gunning fog index, developed by Robert Gunning (1952), is based on two elements: average sentence length in words and number of words of three syllables or more per 100 words. These two numbers are added and multiplied by .4, and the resulting number is the approximate grade level at which the material can be read. When Gunning began his consulting work with newspapers, he was using the original Flesch formula that counted affixes ((X nning, 1945), and the formula that he later developed resembles the reading ease formula. At the earlier stage in Gunning’s career, the term fog index also had a different meaning—it referred to a “measure of uselessly long and complex words” (p. 12). The main advantage of the Gunning fog index over the Flesch reading ease formula is that the former
Table 7.1
CHART FOR INTERPRETING FLESCH READING EASE SCORES
| Reading Ease Score | Description of Style | Estimated Redding Grade |
| 90-100 | Very easy | 5th grade |
| 80-90 | Easy | 6th grade |
| 70-80 | Fairly easy | 7th grade |
| 60-70 | Standard | 8th and 9th grade |
| 50-60 | Fairly difficult | 10th to 12th grade |
| ! 30-50 | Difficult | college |
| 0-30 | Very difficult | college graduate |
CHART FOR INTERPRETING FLESCH HUMAN INTEREST SCORES
Human Interest Score Description of Style
0-10 Dull
10-:20 Mildly interesting
20-40 Interesting
40- 50 Highly interesting
60-100 Dramatic
Table from The An of Readable Writing by Rudolf Flesch. Copyright 1949,-1974 by Rudolf Flesch. Reprinted by permission of HarperCollins Publishers Inc.
gives a grade level immediately while a reading ease score has to be looked up in a table to produce a grade level.
In another step of simplification, Wayne Danielson and Sam Dunn Bryan (1963) developed a computerized readability formula in which the computer does the counts and the computations and gives a readability score. The formula is based on two elements that are similar to the two in the Flesch reading ease formula except that they are defined in units that the computer can recognize easily. They are: average number of characters per space (essentially a measure of word length) and average number of characters per sentence (essentially a measure of sentence length). The resulting score is very much like a reading ease score and in fact can be looked up on the Flesch reading ease chart.
Initially, in order to use the Danielson and Bryan computerized formula, you had to have the written material you wanted to analyze punched on cards, paper tape, or some other means of input that the computer could read. In some cases, this required keyboard- ing by hand. But in the case of wire copy such as that provided by the Associated Press, the hand keyboarding was not necessary. Wire copy is normally available in the form of punched paper tapes that can be used to operate a typesetting machine in a newspaper building. Danielson discovered that it was necessary to modify the tape punching machine only slightly for the paper tapes to be read directly into a computer. This allowed him to study the readability of the Associated Press output for a week without keyboarding the material. Today most wire service copy is transmitted as electrical impulses to be stored in computer memory banks, making it easy to apply computerized readability formulas, to it.
Also available are tables that eliminate the computation necessary to apply the Flesch reading ease and human interest formulas (Farr & Jenkins, 1949). To determine the reading ease score of a sample, you simply look up the average sentence length at the side of the table and the number of syllables per 100 words across the top of the table. Where the row ?nd the column intersect can be found the reading ease score. A similar table for the human it terest score has percentage of personal sentences at the side and percentage of personal words across the top.
Using a Formula:
An example will help to bring out exactly how the Flesch reading ease formula can be applied to a piece of writing. We will take a sample of writing and make the necessary counts and do the computations to come up with a reading ease score. Before we begin, we need to present exact definitions of some of the things we will be counting. Flesch defines a word as a letter, number, symbol, or group of letters, numbers, or symbols surrounded by white space. Thus, 1949, C.O.D., and unself-conscious would all be counted as words. Flesch defines a sentence as a unit of thought that is grammatically independent and is usually marked by a period, question mark, exclamation point, semicolon, colon, or dash. Syllables are counted the way you would pronounce the word. For example, 1916 would count as a four-syllable word. Since you need to find the number of syllables per 100 words, one shortcut that is sometimes useful is to start by writing down 100 and then count only the words of two syllables or more, writing down a 1 for a two- syllable word, a 2 for a three-syllable word, and so forth. 1 hen you simply add all the numbers you have written down, including the 100. This can often save time because many words have only one syllable. Writing down the number of syllables for each word permits you to go back and check your work.
Now we are ready to apply the reading ease formula to the following sample—the beginning paragraphs of a news story written by a student.
The Texas Water Rights Commission (TWRC) voted Tuesday to allow the South Texas Nuclear Project the use of Colorado River water despite a warning from Atty. Gen. Johr -till that such action could result in state instituted court proceedings against TWRC.
Hill’s warning came at the commission’s meeting, after he advised it that the Lower Colorado River Authority (LCRA) had no control over the unallocated waters involved in a debate between LCRA ana TWRC and should not be paid for the use of them.
The debate stemmed from a dispute between TWRC, which controls all the unallocated water in the state, and LCRA, which has power over all Colorado River water within a 10-county area, over who would profit from sale of the water.
This sample is more than 100 words long, so it is adequate to illustrate the workings of the formula, although you would probably measure the entire story if you were seriously attempting to determine its readability.
First, it is necessary to determine the average sentence length (si). Remember that LCRA, TWRC and 10-county should count as one word each. The sample contains 3 sentences and 124 words. Dividing 124 by 3 gives an average sentence length of 41.33 words.
Next, it is necessary to determine the number of syllables per 100 words (wl). The easiest way to determine this is to count the syllables in the first 100 words. The 100th word is the word the before the word state in the third paragraph. The only tricky parts in counting the syllables might be the word TWRC, which includes six syllables when it is pronounced, and the words Atty. and Gen., which include three syllables each when pronounced in full. The number of syllables in the first 100 words is 189.
Next, we substitute these numbers for si and wl in the reading ease formula, and obtain the following:
R.E. = 206.835 – .846(189) – 1.015(41.33)
Performing the two numbers calculations gives the following.
R.E. = 206.835 – i5y.394 – 41.950
And doing the final subtractions gives 4.991, the reading ease score. This is a very low reading ease score. In the reading ease chart in Table 7.1, it falls in the “very difficult” category, where the estimated reading grade is “college graduate.” This is understandable when we look at the long sentences used, the acronyms (LCRA and TWRC), and the use of complicated terms (unallocated water). Of course, if the entire story had been analyzed, the reading ease score might have been higher. News writers often attempt to pack a great deal of information into the beginning of a news story, and this can make the beginning less readable than the rest of the story. This practice can be questioned, however; if the beginning of the story is not readable, people might not get to the later sections.
