Schizophrenia: Reliability And Validity Flashcards
Assessing the validity of the diagnosis and classification of schizophrenia.
Concurrent validity can be achieved by seeing if the two systems of classification (ICD and DSM) agree with each other when they are used to diagnose patients. If there is a lack of agreement between the diagnosis (lower correlation than 0.8) this would suggest one or both systems have not accurately described the disorder.
What is the reliability of the diagnosis and the classification of schizophrenia?
- Refers to whether the systems of classification, such as DSM, can be used by clinicians to constantly make diagnoses of schizophrenia. This depends on a diagnosis of schizophrenia being repeatable.
- Diagnostic reliability could be assessed using inter-rater reliability. This would involve having two separate clinicians diagnose the same group of patients. If there is a strong correlation between the diagnoses of each clinician, then diagnosis is reliable, suggesting the systems of classification used by the clinicians are also reliable.
How has research challenged the reliability and validity of schizophrenia as a diagnostic category?
As part of his classic 1973 study, Rosenhan found that psychiatric hospitals could not distinguish
patients with genuine schizophrenia from the pseudopatients (confederates of his pretending to hear voices but otherwise acting normally) Rosenhan sent to the hospitals. Rosenhan’s research undermines the reliability of the diagnosis of schizophrenia. Given that the
hospitals were inconsistent in their diagnosis (during Rosenhan’s study 83 patients initially
diagnosed with schizophrenia were later reclassified as pseudopatients), this suggests their
diagnoses lacked reliability. Moreover, given that reliability is a necessary precondition for validity,
the failure to reliably diagnose these patients also suggests that the process of diagnosing patients with schizophrenia is also invalid. However, since 1973, the systems of classification and process of diagnosing schizophrenia has changed substantially - a change driven, in part, by Rosenhan’s study. Therefore Rosenhan’s research may lack temporal validity, meaning it may not tell us much (or anything) about the reliability and validity of the classification and diagnosis of schizophrenia today.
What indirect evidence for the validity of the diagnosis and classification of schizophrenia is predictive validity?
More specifically, a type of drug therapy called antipsychotics have been shown to be effective in
treating the positive symptoms of schizophrenia. This suggests that the diagnosis and classification of schizophrenia have some validity. If our
understanding of schizophrenia and its diagnostic criteria were invalid, it would be unlikely that
effective treatments for its symptoms could have been developed. However, antipsychotics are
largely ineffective in treating the negative symptoms of schizophrenia. This indicates that our
understanding of the disorder may still be incomplete, as we have yet to develop treatments that
address all of its symptoms effectively
