The late English psychologist Cyril Burt was known for his studies of the IQ scores of identical twins who were raised apart. The high correlation between the IQs of separated twins in Burt's studies pointed to heredity as a major factor in IQ. (Correlation measures how closely two variables are connected.) Burt wrote several accounts of his work, adding more pairs of twins over time. Here are his reported correlations as he published them.
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Publication
Date/ Twins reared apart/ Twins reared together
1955/ 0.771 (21 pairs) / 0.944 (83 pairs)
1966/ 0.771 (53 pairs) / 0.644 (95 pairs)
What is suspicious here?
In 1966, twins reared together have lower correlation than those raised apart.
The suspicious aspect in the correlation data provided by Cyril Burt is the consistent and identical correlation coefficient of 0.771 for the IQ scores of twins reared apart. The fact that the correlation remains the same across different publications, despite an increase in the number of twin pairs, raises doubts about the reliability of Burt's findings.
Typically, when conducting scientific studies, it is expected to see some variation in results due to factors such as sample size and random variation. In the case of Burt's data, the fact that the correlation coefficient remains the same for twins reared apart, despite the increase in sample size, suggests that the data might be fabricated or manipulated.
Additionally, the correlation coefficient for twins reared together decreases from 0.944 in 1955 to 0.644 in 1966. This discrepancy between the two correlation coefficients is also suspicious and raises questions about the consistency and validity of Burt's research.
It is important to note that subsequent analysis and investigations into Cyril Burt's work have cast doubt on the authenticity and reliability of his findings. It is now widely believed that Burt engaged in scientific fraud by fabricating data and results to support his hereditarian beliefs about intelligence.