4.2 Reliability And Validity In Diagnosis And Classification

Question 1

define co-morbidity

Answer 1

refers to the extent that two (or more) conditions or diseases occur simultaneously in a patient, for example schizophrenia and depression

Question 2

define culture

Answer 2

the rules, customs, morals, child-rearing practices, etc. that bind a group of people together and define how they are likely to behave

Question 3

define gender bias

Answer 3

refers to the tendency to describe the behaviour of men and women in psychological theory and research in such a way that might not be seen to represent accurately the characteristics of either one of the genders

Question 4

define reliability

Answer 4

is consistency - the consistency of measurements.

we could expect any measurement to produce the same data if taken on successive occasions

Question 5

define system overlap

Answer 5

refers to the fact that symptoms of a disorder may not be unique to that disorder but may also be found in other disorders, making accurate diagnosis difficult

Question 6

define validity

Answer 6

refers to whether an observed effect is a genuine one.

Question 7

summarise reliability when looking at diagnosis and classification of schizophrenia

Answer 7

diagnostic reliability means diagnosis must be repeatable(test-retest reliability)
different clinicians should reach the same diagnosis
cultural differences in diagnosis (Copeland), experience of voices (Luhrmann et al.) and ethnic differences (Barnes)

Question 8

summarise validity when looking at diagnosis and classification of schizophrenia

Answer 8

the extent that a diagnosis represents something that is real and distinct from other disorders
gender bias in diagnosis - tendency to pathologies of one gender rather than another
Goldstein and Kreisman - schizophrenic sons more readily seen as ‘ill’ than schizophrenic daughters, accounting for earlier diagnosis of schizophrenia
system overlap - different disorders can share symptoms, making diagnosis difficult
co-morbidity - two or more conditions may co-exist, e.g. ‘schizo-OCD’ (Swets et al.)

Question 9

evaluate reliability and validity in diagnosis and classification of schizophrenia

Answer 9

reliability - lack of inter-rater reliability as low as 0.11 (Whaley) and misdiagnosis of ‘pseudopatients’ (Rosenhan)
unreliable symptoms - psychiatrists found it difficult to agree on what was bizarre and non-bizarre delusion (Mojtabi and Nicholson)
culture can have a protective function - ethnic culture hypothesis tested by Brekke and Barrio
validity - research support for gender bias in diagnosis (Loring and Powell) found males more likely to be diagnosed with schizophrenia
consequences of co-morbidity - co-morbid non-psychiatric diagnoses may compromise treatment and prognosis (Weber et al.)
differences in prognosis - patients rarely share the same symptoms nor the same prognosis