The Principles of Readability gives a brief introduction to the literacy studies in the U.S. and the research on readability and the readability formulas.
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RESEARCH
SummaryOver 80 years of research and testing have contributed to the worldwide use in many languages of the readability formulas.They help us improve the text on the level of words and sentences, the first causes of reading difficulty.The principles of readability are in every style manual. Readability formulas are in every word processor. What is missing is the research and theory on which they stand.
The Principles of ReadabilityWilliam H. DuBay
IntroductionIn 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 7 th 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 10 th 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. 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 tens...