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Factors affecting statistical power in the detection of genetic association
Derek Gordon, Stephen J. Finch
Derek Gordon, Stephen J. Finch
Published June 1, 2005
Citation Information: J Clin Invest. 2005;115(6):1408-1418. https://doi.org/10.1172/JCI24756.
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Factors affecting statistical power in the detection of genetic association

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Abstract

The mapping of disease genes to specific loci has received a great deal of attention in the last decade, and many advances in therapeutics have resulted. Here we review family-based and population-based methods for association analysis. We define the factors that determine statistical power and show how study design and analysis should be designed to maximize the probability of localizing disease genes.

Authors

Derek Gordon, Stephen J. Finch

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Figure 4

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Power loss (PL) for genetic association as a function of errorless power...
Power loss (PL) for genetic association as a function of errorless power threshold and error probability ε. In this figure, we compute statistical power for the χ2 test of independence on 2 × 3 contingency tables in the presence of genotype errors. Power is computed as a function of power without errors (2 settings for power used: 99% and 80%) and an error model parameter ε. This parameter is the probability that a homozygote is misclassified as a heterozygote and the probability that a heterozygote is misclassified as a homozygote. It is assumed that homozygotes are not misclassified as other homozygotes (113). We consider 3 settings for the parameter ε: 1%, 3%, and 5%. Each bar represents 2 values: power in the presence of errors (black portion of each bar) and PL, which is the difference of the power without errors and the power in the presence of errors (represented graphically as the red portion of each bar). Genotype frequencies for cases and controls are computed assuming the following genetic model parameters: f0 = 0.01, f1 = f2 = 0.02, pd = p1 = 0.1, D′ = 1.0. That is, we assume a dominant underlying disease inheritance for the disease where the SNP marker locus is the disease locus. For a power of 99% at the 1% type I error rate, a minimum of 606 cases and 606 controls are required, given that we have equal numbers of cases and controls. Similarly, for a power of 80%, a minimum of 307 cases and 307 controls are required.

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ISSN: 0021-9738 (print), 1558-8238 (online)

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