IB Psychology HL 1.1.4 Measurement Questions

Refer to the paper 2 assessment criteria when awarding marks.
The command term "discuss" requires candidates to offer a considered and balanced review that addresses various aspects of validity and reliability of diagnosis. Conclusions should be presented clearly and supported by appropriate evidence. Although a discussion of both validity and reliability is required, it does not have to be evenly balanced to gain high marks.

The terms "validity" and "reliability" need to be consistently and appropriately used throughout the response. Validity is the extent to which the diagnosis is accurate. The key concern is whether diagnostic systems correctly diagnose people who really have particular disorders and do not give a diagnosis to people who do not. In regard to reliability, responses may refer to two types of reliability: inter-rater reliability and test-retest reliability. Inter-rater reliability can be assessed by asking professionals to observe the same person and, using the same classification system, to make a diagnosis. If clinicians make the same decision, the system is reliable. Test-retest reliability indicates whether the same person will receive the same diagnosis if they are assessed more than once by the classification system. Those candidates who refer to a classification system in the discussion of validity and reliability of diagnosis should earn credit.

Examples of research that could be used include:
- studies of inter-rater reliability reveal that some diagnostic categories are more reliable than others, and that diagnosis is more reliable for some types of patients than others (Nicholls et al. 2000).
- Mary Seeman (2007) completed a literature review to examine evidence relating to the reliability of diagnosis over time and found that initial diagnoses of schizophrenia in women, in particular, were susceptible to change as clinicians found out more information about their patients. This research indicates a problem of test-retest reliability with schizophrenia.
- Wakefield et al. (2007) conducted a study that suggested that many life events (e.g. death of loved one, divorce, loss of job) can account for the appearance of some symptoms of depression, but do not meet the criteria for clinical depression. This study addresses the validity of diagnosis.

In practice, professional diagnoses can be influenced by biases and subjective viewpoints of the diagnostician.

If a candidate discusses only validity or only reliability, apply the markbands up to a maximum of [11 marks].