In a study of birth order and intelligence, IQ tests were given to 18- and 19-year-old men to estimate the size of the difference, if any, between the mean IQs of firstborn sons and secondborn sons.

The following data for 10 firstborn sons and 10 secondborn sons are consistent with the means and standard deviations reported in the article. It is reasonable to assume that the samples come from populations that are approximately normal.

Can you conclude that there is a difference in mean IQ between firstborn and secondborn sons? Use the α = 0.01 level.

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104 Firstborn 82 102 96 129 89 114 107 89 103 Secondborn 103 103 103 91 113 102 103 92 90 114 113