51. The nature of the tests of effectiveness that will provide competent evidence depends, to a large degree, on the nature of the control to be tested, including whether the operation of the control results in documentary evidence of its operation. Documentary evidence of the operation of some controls, such as management's philosophy and operating style, might not exist.
Note: A smaller, less complex company or unit might have less formal documentation regarding the operation of its controls. In those situations, testing controls through inquiry combined with other procedures, such as observation of activities, inspection of less formal documentation, or re-performance of certain controls, might provide sufficient evidence about whether the control is effective.