How far the classification system producers the same diagnosis for a set of symptoms. Need of classification system to be reliable the same diagnosis
Validity
Descriptive validity- similar individuals diagno with the disorder
Predictive validity- useful the diagnostic categories are in predicting the right treatment
classification
At least one symptom must be from positive
Symptoms have to be present for at least 6 months with at least one month of active symptoms
Co-morbidity
Having two or more conditions at the same time e.g schizophrenia and depression hard to treat or recognise certain disorder
Symptom overlap
Having symptoms that could be multiple different mental disorders
Problems with reliability
Affected by cultural bias
E.g harrison et al found an over-diagnosis of schizophrenia I’m west India no research found the symptoms however their ethic background may have been misinterpreted
Problems with validity
Rosenhan- group of volunteers to psych unit once admitted behaved normally however the staff couldn’t tell the difference
