The primary responsibility of individuals accountable for testing activities is to ensure that quality is measured accurately. Often, knowing that quality is being measured is enough to cause improvements in the applications being developed. The existence of a test engineer or someone in the organization devoted to test activities is a form of independence, in the loosest definition.
The roles and reporting structure of test resources differ across and within organizations. These resources may be business or systems analysts assigned to perform testing activities, or, less beneficially, they may be test engineers who report to the project manager.
Ideally, the test resources will have a reporting structure independent from the group designing or developing the application in order to assure that the quality of the application is given as much consideration as the project budget and timeline.
The benefits of independent testing can be seen even in the unit testing stage. Often, successful development teams will have a peer perform unit testing on a program or module. Once a portion of the application is ready for integration testing, the same benefits can be achieved by having an independent person plan and coordinate the integration testing.