Kety et al.

Question 1

What was the aim of the experiment?

Answer 1

To find out whether schizophrenia has a genetic component and whether it is more common in biological relatives than adoptive

Question 2

What were the IV and DV?

Answer 2

IV - Schizophrenics and the control group

DV - Whether schizophrenia is more common in biological or adoptive relatiives

Question 3

What was the sample?

Answer 3

• 34 schizophrenic patients (2 monozygotic twins) aged 20-43 taken from the Danish Adoption Register
• 33 mentally healthy controls selected from the Danish Adoption Register

Question 4

What were the participants matched on?

Answer 4

• Age
• Gender
• Social class of the adoptive family
• Age of the adoption

Question 5

What was the procedure?

Answer 5

• Used Danish family records to locate adoptive and biological relatives of participants
• Tracked down 463 relatives and used the mental health register to assess their mental health
• 4 Danish psychiatrists diagnosed family members (blind test - didn’t know which relatives were adoptive or biological)
• Identity revealed and were assigned to Index Adoptive, Control Adoptive, Inddex Biological or Control Biological

Question 6

What were the results?

Answer 6

• Schizophrenia more common in biological relatives than adoptive relatives
• Of the index participants, 8.7% of relatives had schizophrenia
• Of the control participants, 1.9% of relatives had schizophrenia

Question 7

What are the conclusions of the study?

Answer 7

• Schizophrenic adoptees more likely to have schizophrenia in their biological family than adoptive family
• Index participants more likely to have schizophrenia in their family than control participants

Question 8

Is the study generalisable?

Answer 8

Yes because:

• Matched on characteristics
• Used men and women

However:

• Only an age range of 20-43
• Ethnocentric - all Danish

Question 9

Is the study reliable?

Answer 9

Yes because:

• Adoption records = reaccessable
• Medical records

However, schizophrenia is naturally occurring therefore not replicable

Question 10

Is the study applicable?

Answer 10

Yes because it aids in the nature vs nurture argument

Question 11

Is the study valid?

Answer 11

Yes because:

• Blind experiment = valid
• Real adoption cases

However, psychiatrists were sometimes unsure about diagnoses due to only having medical records

Question 12

Is the study ethical?

Answer 12

Yes because nobody was harmed, however the participants may not have consented to their data being used