Suppose another investigator wants to reproduce the results of the

Suppose another investigator wants to reproduce the results of the Amish study. She can recruit 100 subjects with the II genotype and 100 subjects with the ID genotype. How much power will the study have if the underlying mean and sd in each genotype group are the same as in Table 8.19 and we use a two-sided test with α = 0.05?


Cardiovascular Disease

Lipolysis is a regulator of energy metabolism. Genes encoding proteins that regulate energy metabolism through lipolysis are likely to play an important role in determining susceptibility to metabolic disorders. A study was performed sequencing 12 lipolytepathway genes in an Amish population (Albert et al. [11]). A 19 base pair (bp) deletion was identified in one of the genes that was present in approximately 5% of the Amish population and 0.2% of the non-Amish population of European descent. The deletion was genotyped in 2738 Amish persons, of whom 140 were heterozygous for the deletion (i.e., the ID genotype), 1 was homozygous (i.e., the DD genotype), and 2597 persons did not have the deletion (i.e., the II genotype). In Table 8.19, we compare the mean HDL cholesterol between subjects with the ID vs. II genotypes.

Table 8.19: Mean HDL cholesterol according to LIPE deletion genotype

 LIPE deletion Mean t sd* genotype II 55.2 2597 15.0 49.0 13.3 140 ID


+ mg/dl