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# BEWARE - Edexcel A2 Errors in popular textbook Watch

1. Before I start with what I have to say, I would like to point out that the textbook I am referring to is this one.

One of the two mistakes I have found is that on the table about Gottesman's study (found on page 109), the relationship risk of monozygotic twins having schizophrenia is written as 48% and for Dizygotic twins, the concordance rate is written as 17% However, according to the edexcel mark schemes for the June 2015 paper, the concordance rate for monozygotic twins is actually 50% not 49% and for Dizygotic twins the concordance rate is actually 15% not 17%.

The second mistake I have found is on page 115 and the part I am referencing is the table with the Holland et al results. According to the actual study, the results of the concordance rate is 55% for monozygotic twins and 7% for dizygotic twins unlike the 56% and 5% which is written in the books.

I would like to use this thread as a place where other students can help compile corrections in the book with links to the correct sources as evidence.
2. (Original post by SaranethPrime)
Before I start with what I have to say, I would like to point out that the textbook I am referring to is this one.

One of the two mistakes I have found is that on the table about Gottesman's study (found on page 109), the relationship risk of monozygotic twins having schizophrenia is written as 48% and for Dizygotic twins, the concordance rate is written as 17% However, according to the edexcel mark schemes for the June 2015 paper, the concordance rate for monozygotic twins is actually 50% not 49% and for Dizygotic twins the concordance rate is actually 15% not 17%.

The second mistake I have found is on page 115 and the part I am referencing is the table with the Holland et al results. According to the actual study, the results of the concordance rate is 55% for monozygotic twins and 7% for dizygotic twins unlike the 56% and 5% which is written in the books.
they usually allow 2%-/+

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Updated: April 28, 2016
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