Abnormal Psychology – PSY404 VU
©Copyright Virtual University of Pakistan
73
LESSON 17
EVALUATING SYSTEMS
Reliability
• Reliability refers to the consistency of measurements, including diagnostic decisions.
• One important form of reliability, known as inter-rater reliability, refers to agreement among
clinicians.
Validity
• Validity refers to the meaning or importance of a measurement—in this case, a diagnostic decision.
• Validity is, in a sense, an index of the success that has been achieved in understanding the nature of
a disorder.
• Etiological validity is concerned with factors that contribute to the onset of the disorder.
• Concurrent validity is concerned with the present time and with correlations between the disorder
and other symptoms, circumstances, and test procedures.
• Predictive validity is concerned with the future and with the stability of the problem over time.
• Each time the DSM-IV-TR is revised, new categories are added and old categories are dropped,
presumably because they are not sufficiently useful.
Problems and Limitations of the DSM-IV-TR System
DSM-IV-TR does not classify clinical problems into syndromes in the simplest and most beneficial way.
• One of the important issues involves comorbidity, which is defined as the simultaneous
appearance of two or more disorders in the same person.
• Co morbidity rates are very high for mental disorders as they are defined in the DSM system.
Basic Issues in Assessment
Purposes of Clinical Assessment
• Psychological assessment is the process of collecting and interpreting information that will be
used to understand another person.
• Three primary goals guide most assessment procedures: making predictions, planning treatments,
and evaluating treatments.
• Different assessment procedures are likely to be employed for different purposes.
Assumptions about Consistency of Behavior
• Psychologists must be concerned about the consistency of behavior across time and situations.
• They want to know if they can generalize about the person’s behavior in the natural environment
on the basis of the samples of behavior that are obtained in their assessment.
• Psychologists typically seek out more than one source of information when conducting a formal
assessment.( observation, interview, and psychological tests )
• Because we are trying to compose a broad, integrated picture of the person’s adjustment, we must
collect information from several sources and then attempt to integrate these data.
• One way of evaluating the possible meaning or importance of this information is to consider the
consistency across sources.
Evaluating the Usefulness of Assessment Procedures
• In the case of assessment procedures, reliability can refer to various types of consistency.
• For example, the consistency of measurements over time is known as test–retest reliability.
• The internal consistency of items within a test is known as split-half reliability.
• The validity of an assessment procedure refers to its meaning or importance.
• Is the person’s score on this test or procedure actually a reflection of the trait or ability that the test
was designed to measure?
docsity.com
