Psychological Assessment

Diagnosis. The primary diagnostic guide for mental health professionals is the Diagnostic and Statistical Manual of Mental Disorders, fourth edition (DSM-IV; 1994), which includes specified criteria for several hundred mental disorders and encourages a full multiaxial diagnosis, including information on clinical disorders, personality disorders, medical conditions, psychosocial stressors, and a global assessment of functioning. However, whereas the DSM-IV has separate sections for childhood and adult disorders, there is no specific section on, or criteria for, mental disorders in later life.

Psychometric concepts. The primary psychometric concepts regarding psychological assessment of older adults include the topics of reliability, validity, standardization, and norms.

Reliability. Reliability refers to the degree to which measurement is consistent and stable over time. For example, a reliable psychological test yields consistent scores when a person retakes the test after an interval, usually several days to weeks. Internal consistency reliability is a measure of the extent to which items in a test are interrelated with each other. Test-retest reliability refers to the extent to which test scores are consistent from one administration to the next. Tests used with older persons should show ample evidence of reliability, since this is the first requirement for good measurement.

Validity. Validity refers to the extent to which a test measures what it purports to measure and the extent to which the test can be used to make accurate predictions. For example, does an anxiety test for older persons truly measure anxiety? Reliability and validity are closely inter-twined, as reliability is a necessary, but not sufficient, condition for validity. An unreliable test cannot possibly be valid, although it is possible for a test to have good reliability but poor validity if the test does not measure anything meaningful. The primary types of validity for psychological tests are content, construct, predictive, and concurrent validity. One should make sure that the tests one is using have been well validated in an elderly sample that is similar to the sample from which the respondent comes. Caution should be used in interpreting tests without proven validity among older persons.

Standardization and norms. Scores on most psychological tests rarely provide absolute measures of the construct being assessed (e.g., self-esteem). Rather, tests frequently indicate the relative performance of a respondent when compared to others. Thus, most popular psychological tests are standardized, which means that there are fixed procedures for administration and scoring and that the test has been given to many different people in order to establish statistical norms for age, sex, race, and so on. Norms provide standards for interpreting test scores, so that a person's responses can be compared to an appropriate reference group. Without standardization and norms, it would be impossible to determine if an older adult's score is typical, above average, or below average, making the assessment worthless.

Tests developed specifically for older adults (e.g., the Geriatric Depression Scale) have excellent norms. Likewise, standard intelligence tests have extensive age norms. Many other psychological tests did not initially furnish norms for older adults, but researchers have since provided good age-norms for some of them. Unfortunately, some tests still have missing or inadequate norms for older persons. Clinicians and researchers are encouraged to carefully review the technical manual of tests they use to determine if evidence for reliability, validity, and relevant norms for older persons are available. If not, they should be cautious in interpreting scores.