Reliability and Validity In Diagnosing Schizophrenia
Reliability- level of agreement/consistency on the diagnosis by different psychiatrists across
time and cultures; stability of diagnosis over time given no change in symptoms
Tests for Reliability;
A) Over Time = Test Re-Test Reliability
E.g-
-Beck (1962) DSM; 54% CR
-Soderberg (2005) DSM; 81% CR
➢ symptoms are now more specific as DSM is updated
B) Over Cultures = Inter-Rater Reliability
E.g- DSM= American classification system ICD= European classification system
-Soderberg (2005) DSM; 81% CR
-Nillson (2000) ICD; 60% CR
➢ Different tools in different cultures-> due to different symptoms
➢ DSM>ICD- symptoms may be more specific in DSM
Validity- the extent to which schizophrenia is a unique syndrome with characteristics, signs
and symptoms; how accurate the diagnosis is
Issues of Validity;
Co-morbidity- patients who suffer from schizophrenia and depression for example 1)
Symptom Overlap- Symptoms of schizophrenia are also symptoms of other mental
illnesses, for example Autism, a developmental disorder, has the overlapping
symptoms with the negative symptoms os schizophrenia.
Gender Bias- the criteria is more focused on diagnosing one gender than the other.
The criteria is used differently between males and females.
Cultural Bias- some cultures are more likely to be diagnosed with schizophrenia
than other cultures. Over-diagnosing other cultures with schizophrenia.
Reliability- level of agreement/consistency on the diagnosis by different psychiatrists across
time and cultures; stability of diagnosis over time given no change in symptoms
Tests for Reliability;
A) Over Time = Test Re-Test Reliability
E.g-
-Beck (1962) DSM; 54% CR
-Soderberg (2005) DSM; 81% CR
➢ symptoms are now more specific as DSM is updated
B) Over Cultures = Inter-Rater Reliability
E.g- DSM= American classification system ICD= European classification system
-Soderberg (2005) DSM; 81% CR
-Nillson (2000) ICD; 60% CR
➢ Different tools in different cultures-> due to different symptoms
➢ DSM>ICD- symptoms may be more specific in DSM
Validity- the extent to which schizophrenia is a unique syndrome with characteristics, signs
and symptoms; how accurate the diagnosis is
Issues of Validity;
Co-morbidity- patients who suffer from schizophrenia and depression for example 1)
Symptom Overlap- Symptoms of schizophrenia are also symptoms of other mental
illnesses, for example Autism, a developmental disorder, has the overlapping
symptoms with the negative symptoms os schizophrenia.
Gender Bias- the criteria is more focused on diagnosing one gender than the other.
The criteria is used differently between males and females.
Cultural Bias- some cultures are more likely to be diagnosed with schizophrenia
than other cultures. Over-diagnosing other cultures with schizophrenia.
