asypow {survSNP}

Calculating the asymptotic power and variance

Description

This function calculates the asymptotic power and variance assuming that the survival distribution is a mixture of exponentials with rates and the censoring distribution is uniform on the interval (a,b).

Usage

asypow(n, theta, a, b, lambda0, q, p, alpha, z,exactvar)

Arguments

n

Sample size

theta

Effect size (log genotype hazard ratio (GHR))

a

Censoring distribution parameter (assumed to be uniform on [a,b])

b

Censoring distribution parameter (assumed to be uniform on [a,b])

lambda0

Baseline exponential hazard rate

q

Relative risk allele frequency

p

Relative genotype frequency

alpha

Nominal two-sided type I error rate

z

Genotype scores (right now only additive scores AA=0,AB=1,BB=2 generate correct power)

exactvar

Indicator for using the exact variance formula

Details

This function is called by sim.snp.expsurv.power to calculate the asymptotic variance (exact and approximate) formulas. It is not intended to be called directly by the user. To conduct power calculations, use sim.snp.expsurv.power or the convenience wrapper function survSNP.power.table.

Value

power

Asymptotic power based on exact variance formula

power0

Asymptotic power based on approximate variance formula

v1

First term of asymptotic variance

v2

Second term of asymptotic variance

v12

Third term of the asymptotic variance (covariance)

vapprox

Approximate asymptotic variance formula (=v1)

exact

Exact asymptotic variance formula (=v1+v2+v12)

diff

Difference between variances (=v2+v12)

ratio

Ratio of variances (=v1/(v1+v2+v12))

Author(s)

Kouros Owzar, Zhiguo Li, Nancy Cox, Sin-Ho Jung and Chanhee Yi

References

Kouros Owzar, Zhiguo Li, Nancy Cox and Sin-Ho Jung. Power and Sample Size Calculations for SNP Association Studies with Censored Time-to-Event Outcomes. https://onlinelibrary.wiley.com/doi/full/10.1002/gepi.21645