Certification is a ''procedure by which a third party gives written assurance that a product, process or service conforms to specified requirements."23 It is, by definition, exclusively a third-party activity. In the past, the manufacturer's declaration of conformity was sometimes referred to as "self-certification." The term caused confusion, however, and has been dropped both internationally and by the American National Standards Institute (ANSI) accredited committee for writing certification procedural standards, Committee Z34.24
Certification usually requires performance of product tests. The testing component of U.S. certification activities is included in the industry revenues data in Table 3-1; however, aggregate data on revenues from certification as a whole are not available. Certification is distinguished from testing by three key features. Certification always measures a product (or process or service) against one or more specific standards, whether mandatory, voluntary, or de facto. Testing, by contrast, does not necessarily measure against any specific standard. Second, certification is always performed by a third party, independent of either the supplier or the purchaser. Finally, certification results in a formal statement of conformity—a certificate—that can be used by the manufacturer to show compliance with regulations, meet purchasing specifications, and enhance the product's marketability. The certifier often licenses the manufacturer to print a certification mark on the product or its packaging, potentially increasing its acceptability to the buying public. Certification marks are the property of the certifier and are registered with the U.S. Patent and Trademark Office.25
Certification may encompass many different levels of complexity and expense, depending on the characteristics of the product and the degree of need for confidence in the product's conformity to standards. The more complex and intrusive the certification program is, the greater is its cost.26 In sectors with high demands for safety and reliability, certifiers may require a relatively intensive certification process, involving multiple tests, one or more factor inspections, and testing of large numbers of product samples. Lower levels of need for assurance may be satisfied by type testing—the testing of one or a few samples as typical of all products with the same design and materials. Some certification programs require follow-up testing of additional samples obtained at the factory or on the open market in order to maintain certified status. Evaluation of the manufacturer's quality assurance system is part of some certification schemes, as discussed in the next section.
There are more than 110 private-sector product certifiers in the United States.27 Many private-sector certifiers are also independent testing laboratories. Some certifiers, mainly those operating smaller programs, certify products on the basis of tests performed by other facilities. These tests must be performed by laboratories that are independent of the manufacturer. Whether testing is performed