Considering the keen interest that intermediate readers of all ages can have in technical matters, this literacy gap is troubling. While some highly motivated readers are able to master difficult technical materials, we cannot assume that everyone will do so. To the contrary, the difficulty of technical materials has taught many if not most readers of intermediate skill not to look for technical help in written texts. Helpful text means not only providing readers accurate information but also information written at the reading levels they need.

THE CLASSIC READABILITY STUDIES

The first aim of the classic readability studies was to develop practical methods to match reading materials with the abilities of students and adults. These efforts centered on making easily applied readability formulas which teachers and librarians could use.

The first adult literacy surveys in the U.S. in the 1930s brought new concerns about providing graded texts for adults. For the rest of the century, publishers, librarians, teachers, and investigators addressed that need with new methods of determining the reading level of texts.

The classic readability studies include these landmark issues:

• L. A. Sherman and the statistical analysis of literature.
• The vocabulary-frequency lists
• The classic readability formulas

L. A. Sherman and the statistical analysis of literature

Down through the centuries, many had written about the differences between an "ornate" and "plain" style in English.

In 1880, a professor of English Literature at the University of Nebraska, Lucius Adelno Sherman, began to teach literature from a historical and statistical point of view.

He compared the older prose writers with more popular modern writers such as Macaulay (The History of England) and Ralph Waldo Emerson. He noticed a progressive shortening of sentences over time.

He decided to look at this statistically and began by counting average sentence length per 100 periods. In his book (1893), Analytics of Literature, A Manual for the Objective Study of English Prose and Poetry, he showed how sentence-length averages shortened over time:

• Pre-Elizabethan times: 50 words per sentence
• Elizabethan times: 45 words per sentence
• Victorian times: 29 words per sentence
• Sherman's time: 23 words per sentence.

In our time, the average is down to 20 words per sentence.

Sherman's work set the agenda for a century of research in reading. It proposed the following:

• Literature is a subject for statistical analysis.
• Shorter sentences and concrete terms increase readability.
• Spoken language is more efficient than written language.
• Over time, written language becomes more efficient by becoming more like spoken language.