Readability

What Readability Is

Readability is the ease with which a reader can understand a written text. As a technical writer, your task is to get your reader to engage in reading the document, and to keep your reader reading. This is easier said than done. For example, the average business professional spends about thirty seconds before judging a resume, and about five minutes on a business proposal. This may be because of time constraints, but it’s likely that business professionals scan a document and make a quick judgment based on the document’s appearance or a bit of key information that relates to their interest. Keep in mind that people do not usually read technical writing for pleasure; they read it because they have to—it’s part of their job, or they need to understand instructions or documentation. And since “time is money,” the more difficult the document is to read, the longer it takes, and the higher the “cost.” Your job as the technical writer designer is to make the reading process as easy, clear, useful, and efficient as possible by using all the tools at your disposal to create readable content and design, the two main categories that constitute readability.

While readability definitions and studies usually focus on “regular,” natural language, readability exists in programming languages as well, though in different forms. In programming, things such as programmer comments, choice of loop structure, and choice of names can determine the ease with which humans can read computer program code.

How Readability Developed

In the 1930s, researchers Gray and Leary analyzed 228 variables that affect reading ease and divided them into four types: 1) content, 2) style, 3) format, and 4) organization. By 1940, investigators had:

  • Successfully used statistical methods to analyze reading ease
  • Found that unusual words and sentence length were among the first causes of reading difficulty
  • Used vocabulary and sentence length in formulas to predict reading ease

In the 1940s, Rudolph Flesch created a readability index based on the numbers of words in sentences, the numbers of syllables in words, and the use of personal pronouns (to predict reader interest via personal references).[1] Publishers discovered that the Flesch formulas could increase readership up to 60 percent. Flesch’s work also made an enormous impact on journalism. Later, other researchers updated and simplified Flesch’s formula. The new formula, the Flesch–Kincaid grade-level formula, is one of the most popular and heavily tested formulas even today. It correlates 0.91 with comprehension as measured by reading tests.[1]  There are also many other formulas and indices which focus in some way on readability in terms of words and sentences and provide a grade level needed to understand the text.

  • Flesch-Kincaid
  • Gunning Fog Index
  • Smog Index
  • Automated Readability Index
  • Coleman-Liau Index

Beginning in the 1970s, cognitive theorists began teaching that reading is really an act of thinking and organization. The reader constructs meaning by mixing new knowledge into existing knowledge. Because of the limits of the reading ease formulas, other research looked at ways to measure the content, organization, and coherence of a text. Although this did not improve the reliability of the existing formulas, research into text organization and content showed the importance of these variables in reading ease.

Studies by Walter Kintsch and others showed the central role of coherence in reading ease.[3] Bonnie Meyer showed that people read faster and retain more when the text is organized in topics. She found that a visible plan for presenting content greatly helps readers to assess a text. A hierarchical plan shows how the parts of the text are related. It also aids the reader in blending new information into existing knowledge structures.[4] Bonnie Armbruster found that the most important feature for learning and comprehension is textual coherence, which comes in two types, 1) global coherence, which integrates high-level ideas as themes in an entire section, chapter, or book, and 2) local coherence, which joins ideas within and between sentences. Many other studies looked at the effects of other text variables on ease of reading, including direct and indirect statements, active and passive voice, image use, fonts and layout, and more.

How to Make Technical Documents Readable

A general, non-technical audience’s reading level is between 7th and 11th grade. (The New York Times’ reading level is around grades 12 through 14 – some college). You may use higher reading levels for expert technical audiences. You can always check your document’s reading level with one or all of the indices noted above, to determine if you’re within an appropriate readability range in your document. Note that there will be some variability in results.

 

However, don’t rely only on readability indices to determine whether your document is readable; you are the final arbiter of readability.

Determine the readability of a technical document based on the following characteristics, which are summarized here and explained more fully in subsequent sections of this text. And note that these characteristics are based on the results of readability research from Flesch, Kincaid, Kintsch, Meyer, Armbruster, and many others.

Content

  • Front-load the document so important information occurs first.
  • Explain directly how the information relates to the readers.
  • Define potentially unfamiliar terms.
  • Use simple language whenever possible, and easy-to-read sentence structures.
  • Use short sentences and paragraphs; provide only the necessary information for your purpose and audience.
  • Use transitions or repeated words to link concepts and serve as signposts so your reader knows what to expect.

Design

  • Use headings, subheadings, columns, lists, white space and other visual layout elements to avoid large blocks of text.
  • Use boldface, italics, or other design elements to emphasize key terms.
  • Use a readable, sans serif type font (e.g., Calibri, Arial) of an appropriate size.
  • Insert graphics as appropriate to reinforce key concepts.

A main goal of any technical communicator is to make communications readable, to get your audience to engage in and understand the information as effectively and efficiently as possible.

sample Readability outcomes

The first paragraph on this page was tested at a free site, Readability Formulas, which tests with multiple indices. The reading level of the first paragraph is 12th grade, which is appropriate for students in a college course. Below are the results:

Flesch Reading Ease score: 52.4 (text scale)
Flesch Reading Ease scored your text: fairly difficult to read.

Gunning Fog: 15.8 (text scale)
Gunning Fog scored your text: difficult to read.

Flesch-Kincaid Grade Level: 12.2
Grade level: Twelfth Grade.

The Coleman-Liau Index: 10
Grade level: Tenth Grade

The SMOG Index: 11.2
Grade level: Eleventh Grade

Automated Readability Index: 13.2
Grade level: 18-19 yrs. old (college level entry)

Linsear Write Formula : 16.3
Grade level: College Graduate and above.

 

Readability Consensus

 

Based on (7) readability formulas, we have scored your text:
Grade Level: 12
Reading Level: fairly difficult to read.
Reader’s Age: 17-18 yrs. old (Twelfth graders)
Note that you can also test readability using the Flesch-Kincaid index in Word.

 

[1] Kincaid, J. P., R. P. Fishburne, R. L. Rogers, and B. S. Chissom. 1975. Derivation of new readability formulas (Automated Readability Index, Fog Count, and Flesch Reading Ease Formula) for Navy enlisted personnel. CNTECHTRA Research Branch Report 8-75.

[2] DuBay, W. H. 2006. Smart language: Readers, Readability, and the Grading of Text. Costa Mesa: Impact Information.

[3] Kintsch, W. and J. R. Miller 1981. “Readability: A view from cognitive psychology.” In Teaching: Research reviews. Newark, DE: International Reading Assn.

[4] Meyer, B. J. 1982. “Reading research and the teacher: The importance of plans.” College composition and communication 33, no. 1:37–49.