Gottesman and Shields evaluate

Question 1

Evaluate in terms of reliability.

Answer 1

The methods used to collect the data about the twins were very reliable as they collected secondary data about the participants’ diagnosis of schizophrenia from hospital notes and backed these up with their own examining of the twins, for example through analysing the verbalisations of the twins.

Question 2

Evaluate in terms of validity (artificial?)

Answer 2

A strength of twin studies is that they provide a good natural experiment as nurture is kept constant whilst genetic makeup varies so any differences between twins can credibly be assumed to be due to nature. For example as monozygotic twins were found to have a higher concordance rate for schizophrenia than dizygotic twins this clearly shows that schizophrenia does have a genetic element.

Question 3

Evaluate in terms of ecological validity (true to life?)

Answer 3

It was highly true to life as nothing in the environment was directly manipulated. The findings are naturally occurring and we can therefore generalise the findings to their real situations as they are not artificial.

Question 4

Evaluate in terms of accumptions.

Answer 4

A further weakness of this study is based on the assumption that MZ twins are identical. For example MZ twins are not exactly the same as their fingerprints are different and one twin is typically larger. The reason why MZ twins might not have identical behaviours is that genes turn on and off at different point in life and in interaction with differing environmental experiences; therefore MZ twins may both share a gene or cluster of genes which predispose them to schizophrenia however, only one twin may be exposed to the environmental circumstances which trigger that gene.