Chunk #11 — Mathematical Details — Effective sample size for larger sibships

Source

Effective sample size: Quick estimation of the effect of related samples in genetic case-control association analyses.

Embedded

yes

Text

For Ntri pedigrees each with three siblings, the 3Ntri × 3Ntri correlation matrix can be written as: (4)R=(1rr000.r1r000.rr1000.0001rr.000r1r.000rr1........) and the variance of x, ESS, and sample size reduction are: (5)Varx=σ2(1+2r)3Ntri,NE=3Ntri1+2r and α=11+2r.