Self-report inventories are questionnaires that are used by counselors as part of the diagnostic process. These questionnaires typically ask a series of questions regarding symptoms, feelings, reactions and relationships as a means of learning about the client's issues and their feelings about how those issues are affecting their lives.
These inventories are as effective only as far as the client is honest and truthful when filling it out. Oftentimes, with standardized tests instruments, questions will be repeated in altered forms to act as truthfulness checks.
An example would be an item that asks the individual "I frequently want to hurt myself" (yes/no) and then later on in the inventory asks "I never think about suicide" (yes/no). There are no way that a client can answer both of these questions "yes" or "no." If one is positive, the other has to be negative. Contradictory items such as these can 'catch' someone who is being dishonest or filling out the self-report measure at random.
Examples of self-report inventories include the Minnesota Multiphasic Personality Inventory (MMPI) and the Beck Depression Inventory.