Plain Language: Evaluating Document Usability


Ce contenu est offert en anglais seulement.

Heather Matsune
(Language Update, Volume 4, Number 4, 2007, page 13)

In our previous two articles, we covered the basics of readability and intelligibility. Although applying those two concepts virtually guarantees that your documents will be clear, you may have more work to do to make sure they’re effective. Of course, to be effective, your documents have to be readable and intelligible, but if they aren’t usable too, your message may be lost and all your efforts for clarity will have been in vain. Therefore, evaluating the usability of your documents is an essential part of the writing process.


When you write, do you think about how well your readers will be able to use and retain the information in your document? Few of us do, even though a document that is usable from both a physical and a cognitive standpoint will be more effective in communicating your message.

Physical usability

To evaluate the physical usability of a document, you need to distance yourself from the text and focus on its material qualities—whether it is easy or difficult to physically handle.

For example, this week you need to read your organization’s annual report. The language may be perfectly clear and the information relevant and structured, but you still can’t read it all the way through. Why do you suppose that is? It could be something as simple as the finish on the paper: too high a gloss can tire out your eyes fast. With any kind of print document, factors such as the finish and weight of the paper have an impact on physical usability. In this case, a matte finish could make the document more usable.

Here’s another example: you’re writing a historical document that refers to a number of Canadian cities. You include a map at the end of your document as a visual aid. It’s a legitimately good idea, but the unfolded map measures 50 by 75 centimetres. Needless to say, even if your readers had enough room to open up the map, most of them couldn’t be bothered. In this case, it would have worked better to insert smaller maps into the document at the point where you mention each city.

Cognitive content

Presenting information so that it is easy for the brain to process increases the usability of your document. If you use the writing strategies below, you can reduce the amount of thinking your readers have to do.

  • Lower the level of inference: be explicit

    When your message isn’t explicit, your readers have to infer the meaning, making assumptions and drawing their own conclusions based on the information available to them. Consider the following example:

    You have created a form with a note at the bottom that says, "Please send in this form after you fill it out." Yes, but where, when and how? Leaving out information can generate a lot of errors and complaints.

  • Eliminate distractors

    A distractor is any piece of information that your readers could confuse with the information they are looking for in a document. Too many distractors make it harder to use the document and retain the information in it.

    To renew your subscription, send in your order form by 2007-05-06. If this is your first order, please send a photocopy of your driver’s licence with your form by 2007-04-02. Your subscription will expire on 2008-12-11.

    The three dates in this short paragraph can easily distract readers and even mislead them—they may not know which number is the month and which is the day.

  • Send readers to as few internal and external references as possible

    References within a document (footnotes, asterisks) or to other documents increase the complexity of the reading task.

    For instance, if you are writing a technical manual for the general public, don’t explain all the terms in a glossary at the end of the document. Instead, define each term after it appears for the first time or in a sidebar on the same page.

  • Make sure your information is easy to follow

    For example, use a numbering system (section 1, 2) instead of letters (section A, B). Readers filling out section G of a form won’t instinctively know that they are working on the seventh part of the document.

    Another strategy is to put figures and calculations in columns or rows. That kind of set-up helps the brain process numeric and mathematical information more quickly.


You can write and design a good document, but the only way to know for sure that it’s effective is to test it with actual readers. Before you distribute your document, make sure that a sample of your readers understands the vocabulary and key messages well enough to use it properly. Usability testing shows how well actual or potential readers understand a document, but more to the point, how well they can do what the document instructs them to do.

Types of usability tests

You can take several approaches to usability testing, and you should! By using more than one type of test, you will get more in-depth information on the quality of your document. Three common types of usability tests are focus testing, written questionnaires and one-on-one interviews.

Focus testing

Focus testing is a market research technique in which you assemble a group of people for a moderated discussion about a document, service or other product in order to gather opinions. It’s a valuable marketing tool, but on its own it doesn’t tell you enough about usability. Because reading is typically a solo effort, evaluating a document in a group setting may produce unreliable results. For instance, readers who don’t understand the document probably won’t admit it, or they may work with other readers to figure out what they’re supposed to do. Focus testing reflects unrealistic reading situations and generates superficial feedback.

Written questionnaires

Using a written questionnaire involves having readers fill out a form to evaluate their comprehension of a document. Because the questions are mostly multiple choice, the range of responses is limited. The upside of questionnaires is that your data is easy to quantify, which is helpful if you want to produce statistical reports. However, written questionnaires may come across as having right and wrong answers and may be intimidating for people with low literacy.

One-on-one interviews

One-on-one interviews are probably the most effective type of usability test because you can collect detailed, reliable feedback from one person at a time. In this type of testing, you ask a reader questions about a document to determine whether he or she has understood it, as well as observe the reader using the document in order to identify areas in need of improvement.

It can cost you five times less to conduct one-on-one interviews than a series of focus tests. So, with one-on-one interviews, the return on investment is greater than with focus testing because it costs less to deal with a dozen or so people than the larger sample you need for focus testing. The only real drawback of one-on-one interviews is that they can be more time-consuming than other types of testing, which is why it’s best to use a combination of types of usability tests.


Although testing will improve usability, there’s simply no such thing as a perfect document. Invariably there will be a problem that no one notices, or a policy or some statistics will change and you’ll have to update your document. Therefore, you need to be set up to make changes after the fact. If you create a procedure for collecting and responding to feedback from your readers, you will be able to improve your document continually.

By allowing your readers to participate in the development process, you significantly increase their chances of being able to read, understand and, in the end, use your documents.

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