Testing, Testing, 1, 2 3

Verify the manual, as well as the product

by Robert J. Carrico

Just as it is important that a product function properly, the product manual must also work. Owners or product users must be able to easily find information they need to use an item effectively.

To achieve this objective, the manual’s content must be clear and its organization beyond reproach. Unfortunately, product manual writers and product users do not always think the same way.

Proper content and organization might seem like a given, but there are often inherent differences between the mind-set of the writer and that of the reader. These differences can stand in the way of creating a truly useful document and are likely to affect the manual’s organization more than its content. Manuals are usually written by someone who is an expert in the way the product works, while users are often novices.

Expert and novice differences in thinking have been the focus of an impressive body of research that began around 1965.1,2 In applying this research to product development, we could conclude that someone with an expert’s knowledge of a particular product would think about that product in terms of patterns, integrated components and abstract relationships. The novice user of the product, on the other hand, would reason about it in terms of individual components that are concrete and visible.

Shedding some light

As an example of these differences, I wanted the interior overhead light of my new sport utility vehicle to come on when I opened the door. The overhead light section of the owner’s manual indicated that the three-position switch ("off," "door" and "on") needed to be in the "door" position, which it was. What this section of the manual did not say was that a control on the front instrument panel must be set in a particular position for the overhead light to be triggered by the opening of a door.

I learned of this requirement only after calling the dealership. The control setting was indeed mentioned in the owner’s manual, but it appeared in the instrument panel section. This placement probably made perfect sense to the expert who wrote the manual and understood the relationship between these two components. It didn’t, however, make sense to me, the novice who was trying to get the light to come on and who didn’t know of this relationship. I only thought to look it up in the overhead light section of the manual.

This is an example of a product with excellent quality and a manual with all the necessary information. The issue is where that information is located in the manual.

Testing, 1, 2, 3

The product manual, then, should be tested, along with the product. This should be performed by a combined effort of experts who thoroughly understand the product and novices who do not. The experts—preferably not the same ones who wrote the manual—should establish the test objectives and plan. The novices should use the manual to guide them in the product’s intended function, solve problems that are encountered and answer questions.

The novices could be representative users of the product within the company, or they could be potential customers, perhaps in the form of a focus group. Another approach would be forming a test group within the company whose mission and skill is that of product manual testing. 

In general, almost any form of documentation intended for non-experts could benefit from this approach. This is consistent with a true customer-centered design process, as it forces the writer to focus on the thought process of the customer, especially with respect to the organization of the document.


  1. Adriann de Groot, Thought and Choice in Chess, Mouton, 1965.
  2. J.H. Larkin, "Processing Information for Effective Problem Solving," Engineering Education, Vol. 70, No. 3, 1979, pp. 285-288.

Robert J. Carrico is president and owner of Carrico & Associates in Franklin, MI, where he designs information and quality systems. He earned a doctorate in cognitive psychology and a master’s degree in mathematical statistics from Wayne State University in Detroit. He is a member of ASQ and is a certified quality engineer, reliability engineer and auditor.

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