Some research suggests that first born children may have higher IQ scores than their later born siblings. Do first-born identical twins have higher IQ scores than their second-born sibling? Data from a 1998 study were analyzed to determine whether first-born identical twins have higher IQ scores than their second-born siblings. Ten pairs of adult identical twins were assessed and their Full Scale IQ scores were calculated. Source: M. J. Tramo, W. C. Lodtus, T. A. Stukel, R. L. Green, J. B. Weaver, and M. S. Gazzaniga. “Brain Size, Head Size, and Intelligence Quotient in Monozygotic Twins.” Neurology 50, 1246–52. Let μ1 and μ2 represent the mean Full Scale IQ score for all first-born identical twins and second-born identical twins, respectively, and let μd be the mean of the differences in IQ score of all identical twins (IQ score of first-born twin minus IQ score of second-born twin). Which of the following are the appropriate null and alternative hypotheses?
H0: μd = 0
Ha: μd > 0
H0: μd = 0
Ha: μd < 0
H0: μd > 0
Ha: μd = 0
H0: μ1= μ2
Ha: μ1 > μ2
