Validity of diagnosis (types of validity)

Question 1

Etiological validity

Answer 1

This is established by examining what is known about the causes of the disorder and matching them to the person’s history

If there is a known genetic component, the clinician should look for family history to support the diagnosis

Can be difficult to obtain because symptoms can vary, e.g. with Sz

Question 2

Concurrent validity

Answer 2

This is checked by looking at another diagnostic tool such as comparing the ICD and DSM

If there is a broad agreement about which symptoms are involved in which disorders, there is broad concurrent validity

Question 3

Predictive validity

Answer 3

This is when the future course of the disorder is known and can be applied to the patient

The diagnosis can be checked against the outcome to see if it was valid

E.g. if a depression diagnosis was accurate the person should improve within 8 weeks of taking prescribed antidepressants

Different therapies work differently for different patients so there is a chance it will be ineffective even when the diagnosis is correct

Question 4

Convergent validity

Answer 4

This is when 2 measures of the same construct agree with one another

A correlation test will be carried out

E.g. looking at signs, symptoms and courses of an illness then how someone response to treatment, family history and other measures