asypow (version 2015.6.25)

info.expsurv.kgroup: Expected Information Matrix for a Single or Multiple Group Clinical Trial with Exponential Survival

Description

Calculates expected information matrix for a single observation for a single or multiple group clinical trial with exponential survival.

The clinical trial will accrue subjects over a time period $L$. Each subject will enter the study at a random time between 0 and $L$, so the subject's follow up time, $U$, will be uniformly distributed between 0 and $L$. A subject with follow up time $U$, can die at a time $t$ between 0 and $U$, or the subject can be withdrawn alive at time $U$. The density of time to death is exponential distribution with hazard, $w$.

Usage

info.expsurv.kgroup(w, L, group.size=1)

Arguments

w

Scalar or vector of exponential rates (reciprocals of the mean survival time ) for the groups. The i'th component is the (alternative hypothesis or true) rate of the i'th group.

L

The length of the clinical trial. If all groups have the same trial length, L should be a single number; otherwise, L should be a vector the same length as w where L[i] is the length of the clinical trial for the i'th group.

group.size

Needed only if there are to be several groups with unequal sample sizes. The value of the i'th component is the relative sample size of the i'th group. The calculation made is for a single observation spread over the several groups in proportion to the specified sample size. If this value is specified, it should be a vector of the same length as lambda.

Value

Expected information matrix for a single observation. The matrix is square with dimension equal to the number of groups.

References

Cox, D.R. and Hinkley, D.V. (1974). Theoretical Statistics Chapman and Hall, London.

See Also

info.binomial.kgroup, info.poisson.kgroup, info.ordinal.kgroup

Examples

# Find the information matrix for a clinical trial of
# length 3 with hazard 1
info.expsurv <- info.expsurv.kgroup(1, 3)
print(info.expsurv)