Discuss validity and reliability of diagnosis

Diagnosis

Diagnosis within abnormal psychology means identifying and classifying abnormal behavior on the basis of • symptoms, • the patients’ self-reports, • observations, • clinical tests • other factors such as

information from relatives.

Discuss validity and reliability of diagnosis

Why Diagnose?

• Diagnosis involves matching the results of the psychological assessment with classification systems such as DSM-V.

• The purpose of diagnosis is to find a treatment for the patient and to make a prognosis.

Discuss validity and reliability of diagnosis

Reliability of diagnosis

Discuss validity and reliability of diagnosis

You have learned the symptoms of over thirty disorders……..

• You are going to try to diagnose behavior.

• Use the sheets given.• You SHOULD use your

notes!

• Behavior 1• Behavior 2• Behavior 3• Behavior 4• Behavior 5• Behavior 6• Behavior 7• Behavior 8• Behavior 9

Discuss validity and reliability of diagnosis

Reliability of diagnosis

• Reliability in diagnosis means that clinicians should be able to reach the same correct diagnosis consistently if they use the same diagnostic procedure.

• This is called inter-judge reliability.

Discuss validity and reliability of diagnosis

How can we increase reliability?• Reliability can be improved if

clinicians use standardized clinical interview schedules, which define and specify sets of symptoms to look for.

• But the individual psychiatrist must still make a subjective interpretation of the severity of the patient’s symptoms.

• The introduction of diagnostic manuals has increased reliability of diagnosis over the year even though the manuals are not without flaws. Discuss validity and reliability of diagnosis

Cooper et al. (1972) The US-UK Diagnostic Project

• The aim of the study was to investigate reliability of diagnosis of depression and schizophrenia.

• The researchers asked American and British psychiatrists to diagnose patients by watching a number of videotaped clinical interviews.

Discuss validity and reliability of diagnosis

Cooper et al. (1972) The US-UK Diagnostic Project

• The British psychiatrists diagnosed the patients in the interview to be clinically depressed twice as often.

• The American psychiatrists diagnosed the same patients to be suffering from schizophrenia twice as often.

Discuss validity and reliability of diagnosis

Cooper et al. (1972) The US-UK Diagnostic Project

• The results indicated that the same cases did not result in similar diagnosis in the two countries.

• This points towards problems of reliability as well as cultural differences in interpretation of symptoms and thus in diagnosis.

Discuss validity and reliability of diagnosis

Validity of diagnosis

Discuss validity and reliability of diagnosis

Validity of diagnosis• Validity of diagnosis refers to

receiving the correct diagnosis.

• It is much more difficult to provide a correct diagnosis and give a prognosis for a psychological disorder than for a physical disorder because it is not possible to observe objective signs of the disorder in the same way.

Discuss validity and reliability of diagnosis

Validity of diagnosis

• The DSM-V manual does not include etiology but only symptoms.

• Sometimes patients have symptoms that relate to different psychological disorders so it can be difficult to make a valid diagnosis.

Discuss validity and reliability of diagnosis

Discuss validity and reliability of diagnosis

Rosenhan (1973) On being sane in insane places

Aim: • To test reliability and

validity of diagnosis in a natural setting. Rosenhan wanted to see if psychiatrists could distinguish between “abnormal” and “normal” behavior.

Discuss validity and reliability of diagnosis

Rosenhan (1973)Procedure: • This was a covert participant

observation with eight participants consisting of five men and three women (including Rosenhan himself).

• Their task was to follow the same instructions and present themselves in 12 psychiatric hospitals in the USA.

Discuss validity and reliability of diagnosis

Rosenhan (1973)

Results:• All participants were

admitted to various psychiatric wards and all but one were diagnosed with schizophrenia.

• The last one was diagnosed with manic depression.

Discuss validity and reliability of diagnosis

Rosenhan (1973)

• All pseudo-patients behaved normally while they were hospitalized because they were told that they would only get out if the staff perceived them to be well enough.

Discuss validity and reliability of diagnosis

Rosenhan (1973)

• The pseudo-patients took notes when they were hospitalized but this was interpreted as a symptom of their illness by the staff.

• It took between 7 to 52 days before the participants were released.

Discuss validity and reliability of diagnosis

Rosenhan (1973)

• They came out with a diagnosis (schizophrenia in remission) so they were “labeled”.

Discuss validity and reliability of diagnosis

Rosenhan (1973)Follow Up

• A follow-up study was done later where the staff at a specific psychiatric hospital were told that impostors would present themselves at the hospital and that they should try to rate each patient whether he or she was an impostor.

Discuss validity and reliability of diagnosis

Rosenhan (1973)Follow Up

Of the 193 patients:• 41 were clearly identified

as impostors by at least one member of the staff

• 23 were suspected to be impostors by one psychiatrist

• 19 were suspected by one psychiatrist and one staff member.

Discuss validity and reliability of diagnosis

Rosenhan (1973)Follow Up

There were no impostors.

Discuss validity and reliability of diagnosis