var.delta.eb: Variance estimation

In SurrogateTest: Early Testing for a Treatment Effect using Surrogate Marker Information

Description

Variance estimation, generally not called directly by the user

Usage

var.delta.eb(Axzero, Adeltazero, Aszero, Bxone, Bdeltaone, 
Bsone, Bxzero, Bdeltazero, Bszero, t, landmark = landmark, 
extrapolate)

Arguments

Axzero	observed event times in the control group in Study A
Adeltazero	event/censoring indicators in the control group in Study A
Aszero	surrogate marker values in the control group in Study A, NA for individuals not observable at the time the surrogate marker was measured
Bxone	observed event times in the treatment group in Study B
Bdeltaone	event/censoring indicators in the treatment group in Study B
Bsone	surrogate marker values in the treatment group in Study B, NA for individuals not observable at the time the surrogate marker was measured
Bxzero	observed event times in the control group in Study B
Bdeltazero	event/censoring indicators in the control group in Study B
Bszero	surrogate marker values in the control group in Study B, NA for individuals not observable at the time the surrogate marker was measured
t	time of interest
landmark	landmark time of interest, t0
extrapolate	TRUE or FALSE; indicates whether local constant extrapolation should be used, default is TRUE

Details

Variance estimation using the closed form expression under the null hypothesis of no treatment effect; more details are included in the documentation for early.delta.test.

Value

Variance estimate for √{n_{B}}\hat{Δ}_{EB}(t,t_0)

Author(s)

Layla Parast

References

Parast L, Cai T, Tian L (2019). Using a Surrogate Marker for Early Testing of a Treatment Effect. Biometrics, 75(4):1253-1263.

Examples

data(dataA)
data(dataB)

var.delta.eb(Axzero = dataA$x0, Adeltazero = dataA$delta0, 
Aszero = dataA$s0, Bxone = dataB$x1, Bdeltaone = dataB$delta1, 
Bsone = dataB$s1, Bxzero = dataB$x0, Bdeltazero = dataB$delta0, 
Bszero = dataB$s0, t=1, landmark=0.5,  extrapolate = TRUE)

SurrogateTest documentation built on Nov. 16, 2021, 9:10 a.m.