validity and reliability 16 maarker

• Predictive validity

  if diagnosis leads to successful treatment, then diagnosis is valid.
• Descriptive validity

  patients with schizophrenia should differ in symptoms from patients with other disorders
• Criterion validity

  •those diagnosed with schizophrenia differ in predictable ways from those who aren’t diagnosed with it.
• Aetiological validity

  to be valid, all schizophrenics should have the same cause for the disorder. 
• validity sz

  •Diagnosis represents something that is real and distinct from other disorders. Effectively, if the diagnosis of schizophrenia is valid, then patients who are diagnosed with it must have it.

  •Classification systems should measure what they claim to measure which is different disorders.

  •In order for a diagnosis to be valid, it must be reliable.
• reliability sz

  Diagnosis must be repeatable and consistent in symptom

  measurement

  
  

  Reliability in diagnosis refers to the level of agreement that different psychiatrists can achieve on a single diagnosis for an individual, both over time and across cultures, provided that the disorder’s symptoms have not changed
• Test-retest reliability

  occurs when a clinician makes the same diagnosis on separate occasions (different points in time).
• Inter-rater reliability

  occurs when different clinicians make identical, independent diagnoses of the same patient
• Briefly outline issues of reliability in the classification of schizophrenia

  •Reliability in the classification of schizophrenia is that diagnosis must be repeatable and consistent. This may be an issue because the symptoms an individual experiences may not be stable over time and change. This would render the classification system used to diagnose as unreliable because test-retest reliability is low if clinicians cannot arrive at the same diagnosis over time.
• Another issue surrounding the reliability and the classification of schizophrenia is inter-rater reliability. Some clinicians may use the same classification system but do not all arrive at the same diagnosis of schizophrenia. Therefore, misdiagnosis may take place suggesting classification isn’t always reliable
• co-morbidity

  the presence of one or more additional disorders or diseases simultaneously occurring with sz
• gender bias

  •the tendency for diagnostic criteria to be applied differently to males and females
• culture bias

  •the tendency to over-diagnose members of other cultures as suffering from SZ
• symptom overlap

  •the perception that symptoms of SZ are also symptoms of other mental disorders
• gender bias in sz

  Adrocentrism – mentally healthy adult behaviour is based on mentally healthy ‘male’ behaviour – so what adult mental health looks like is representative of a male world view.

  Beta-bias – assuming what is true for men is also true for women so minimising the differences between men and women in terms of the symptoms they show and their ability to deal with the disorder.
• what is culture bias sz

  Concerns the tendency to over-diagnose members from other cultures as suffering from SZ. People from an Afro-Caribbean descent are SEVERAL times more likely than white people to be diagnosed with SZ.

   The rates for diagnosis in America and the UK are high, whilst the rates in Africa and the West Indies is low. Therefore, this begins to rule out genetic vulnerabilities –
• Reliability refers to the consistency of a diagnosis, meaning that different clinicians should be able to reach the same diagnosis when assessing a patient. In the context of schizophrenia (SZ), reliability is assessed through inter-rater reliability (the extent to which different psychiatrists agree) and test-retest reliability (whether the same diagnosis is given over time). 
• The classification of SZ relies on diagnostic manuals such as the DSM-5 and ICD-11, which define the symptoms and criteria required for diagnosis. However, a key issue is that different classification systems have different criteria, leading to inconsistent diagnoses. For example, the DSM-5 needs only one positive symptom (delusions, hallucinations) to be present for diagnosis whereas ICD-10 needs two or more negative symptoms for a diagnosis to occur. This decreases reliability as It may lead to inconsistent diagnosis. 
• Validity is the extent to which schizophrenia is a unique syndrome with characteristics, signs and symptoms. For the classification system to be valid it should be meaningful and classify a real pattern of symptoms, which result from a real underlying cause. One factor affecting validity is the issue of symptom overlap. Symptom overlap complicates the classification of schizophrenia by making it difficult to distinguish from other psychiatric disorders like bipolar disorder, schizoaffective disorder, and major depressive disorder with psychotic features.
• Shared symptoms, such as hallucinations, delusions, and cognitive impairment, contribute to diagnostic ambiguity and frequent misdiagnosis. This challenge has influenced changes in classification systems like DSM-5 and ICD-11, leading to the removal of schizophrenia subtypes due to their poor reliability.
• Cultural differences further reduce reliability and validity in schizophrenia diagnosis. Studies show that African Americans and Afro-Caribbeans are significantly more likely to be diagnosed with schizophrenia than white individuals (Barnes, 2004), even when symptom severity is similar. This suggests diagnostic bias rather than a genuine genetic predisposition.
• In some cultures, auditory hallucinations are considered spiritual experiences rather than symptoms of mental illness, leading to overdiagnosis in Western psychiatry. The influence of culture on diagnosis links to symptom overlap, as different cultures may interpret the same symptoms differently, further complicating the validity of schizophrenia as a distinct disorder.
• Issues with reliability and validity in schizophrenia diagnosis have profound implications. Misdiagnosis can lead to inappropriate treatment, with individuals receiving unnecessary antipsychotic medication while their actual condition remains untreated. Additionally, psychiatric labels carry social stigma, affecting employment, relationships, and self-perception.
• this suggests that an emic construct that only reflects the norms and values of western ideals and therefore a diagnostic system that is culturally biased towards western culture, thus reducing the validity of schizophrenia diadnosis and resulting in an un reliable diagnosis
• • Reliability: Measures consistency. It is about the extent to which psychiatrists can agree on the same diagnoses when independently assessing patients.
• • Validity: Is all about measuring what you want to measure, in our case how accurate diagnosis for schizophrenia is. If you create a test that does not measure schizophrenia then it is not valid.