Schizophrenia Lesson Two

Specification Describe and evaluate two issues in classifying or diagnosing schizophrenia… -Reliability -Validity

Issues in Classification and Diagnosis What might these be?

Learning Objectives To define what is meant by the terms ‘reliability’ and ‘validity’ To discuss how these effect the diagnosis of schizophrenia To be able to assess the reliability and validity of diagnosing schizophrenia using research evidence

Reliability How can we define reliability? Test Retest Reliability = Inter-rater reliability =

AO2/3 Marks We have lots of information/key words/descriptive knowledge How are we going to get the AO2/3 marks? Research!!!

Inter-rater reliability – do psychiatrists agree? Beck et al (1961) looked at the inter-rater reliability between 2 psychiatrists when considering the cases of 154 patients. The reliability was only 54% - meaning they only agreed on a diagnoses for 54% of the 154 patients! I wonder what the other bloke thinks?

Söderberg (2005) Reported a concordance rate of 81% using the DSM-IV What does this suggest? Inter-rater reliability – do psychiatrists agree? I really hope I agree with that other bloke!

Inter-rater reliability – do psychiatrists agree? There is lots more research based evidence in your textbooks (p ) Summarise these findings in a paragraph In general what does the evidence suggest?

Validity How can we define validity? How can we assess validity?

Testing Validity Reliability – a valid diagnosis has first to be reliable, does this guarantee validity? Predictive Validity – if diagnosis leads to successful treatment, the diagnosis is seen as valid, why is this difficult to attain? Descriptive Validity – to be valid, patients diagnosed with different disorders should differ from each other, why would this be reduced by comorbidity? Example? Aetiological Validity – to be valid, all patients with the same disorder should have the same cause, is it this simple?

On Being Sane in Insane Places Rosenhan (1973) recruited 8 people Each of the 8 people went to a psychiatric hospital and reported only 1 symptom. That a voice said only single words, like “thud”, “empty” or “hollow”. When admitted, they began to act “normally”. All were diagnosed with suffering from schizophrenia (apart from 1). The individuals stayed in the institutions for between 7 to 52 days.

On being sane… follow up Rosenhan told the institutions about his results, and warned the hospital that they could expect other individuals to try & get themselves admitted. 41 patients were suspected of being fakes, and 19 of these individuals had been diagnosed by 2 members of staff. In fact, Rosenhan sent no-one at all!

Rosenhan (1973) What does this study mean in terms of validity of diagnosis? What does this study tell us about the effect of “labelling” BUT… what issues are there with the study?

Cultural Relativism Classification systems reflect WESTERN culture – why might this be a problem?

Homework: Due Monday 15 th Sept. Using the hand-out / textbook / internet research / books in the library etc. Answer the questions: 1.Comment on the differences between the ICD-10 and DSM-IV classification systems and the consequences of this for reliability 2.Explain how reliability may be affected by using different criteria for diagnosis 3.Comment on the differential number of sub-types in DSM-IV and ICD-10 – how does this affect reliability?

Final Check What is Reliability? What is Validity? How can we test reliability? How can we test Validity?