Datasets for Statistical Analysis

Breast milk better for adult intelligence

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Description:

The article focusses on an (observational) study of more than 3000 Danish people born between 1959 and 1961.

Information:

IQ tests admininstered (see above) showed breast-feeding for up to nine months "conferred a long-lasting intellectual benefit." The article continues to say that breast-feeding longer than nine months produced no added benefit.

Later, the article reports the mean IQ of those breast-fed less than one month as 99.4; a mean IQ of 106 for those breast-fed between seven and nine months; and after nine months of breast feeding, the mean IQ dropped to 104.

The article also reports that an IQ score of 100 is better than 50% of the population, and an IQ score of 110 better than 25% of the population.

Source:

Breast milk is better for adult intelligence: study. The Chronicle (Toowoomba, Australia), Saturday May 11, 2002, p 29.

Notes:

As an observational study, no cause and effect can be inferred, despite journalistic intentions. What is the lurking variable? Are the differences statistically significant anyway? Assuming Normal distributions, what standard deviation is inferred for this IQ test?

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