Defining Accessibility Problems in Measurable Terms

Introduction

An aim of this guide is to help you define your accessibility problems in measurable terms. Measures do not necessarily need to be absolute, but they should give you an idea of what to strive for. If there is no measure, then how will you know when you have achieved what you set out to do?

The following examples illustrate un-measurable and measurable problem definitions.

Examples of Accessibility Problem Definitions

An un-measurable problem definition:

The product does not have any features for people who are blind. The product needs additional features so that it will be usable by people who are blind.

Reason:

The problem with this statement is that it uses a term that is scientifically vague, namely, "blind." Many people who are "legally blind" (up to 80% in any given test sample) have some residual vision that they may be able to use to access your product. People who have no vision at all (total blindness), however, may not be able to use the product at all. Thus, a product could be designed to meet this requirement (for up to 80% of test subjects), but it would not solve the true problem, and it would not meet the requirements of the Section 508 legislation.

The problem definition does not include a statement as to whether the users who are totally blind should be able to access all or just some of the features of the product. The problem should define how far the accessibility enhancements need to go on the product.

When the problem states, "the product needs additional features," it anticipates that something needs to be added on to the product. The problem may, however, be solvable by modifying existing features rather than adding new ones, so it is probably best to leave solution-type wording out of the problem definition.

A measurable problem definition:

Operation of the product currently relies on the user having a visual capability. The product needs to be modified so that it can be used without vision for general operation. General operation does not include unpacking, first-time setup, troubleshooting, or maintenance of the product, but it does include access to all functions that are available to all end-users.

For our purposes, "users without vision" are defined as people who do not have the ability to see at all. Eighty percent of users without vision must be able to operate the primary functions of the product (with assistance from a sighted user) within 15 minutes of first introduction to the product, and be able to operate primary functions of the product independently within 30 minutes. For sighted users, 90% of these users must be able to operate the primary functions of the product (with sight) within 5 minutes of first introduction to the product; be able to learn how to use the product in a non-visual manner within 5 more minutes; and be able to operate primary functions of the product without vision in a further 5 minutes.

Reason:

This definition and set of measures is longer, but there is certainly less ambiguity. First, the problem is defined in terms of the operation of the product and the user capabilities that are required to do this. Second, the problem definition is based on the functional limitation ("use without vision") rather than focusing on "people who are blind."

This problem definition includes only people who do not have any vision at all (as opposed to the "legally blind" possibility in the previous example). Note: A separate measure would be required if the product needed to be usable by someone with reduced vision.

Finally, there is acknowledgment that the lack of vision could be because of disability, or it could be from using the product while the user's eyes are busy elsewhere (i.e., when it describes how quickly a sighted user should be able to use the product in a non-visual manner). In this case, the user may reasonably be expected to have some visual familiarity with the product, and this should be acknowledged in the measures.