nbstat1 {lrstat}R Documentation

Negative binomial rate ratio by stratum

Description

Obtains the number of subjects accrued, number of events, number of dropouts, number of subjects reaching the maximum follow-up, total exposure, rate and variance for log rate in each group, rate ratio and variance for log rate ratio by stratum at a given calendar time.

Usage

nbstat1(
  time = NA_real_,
  rateRatioH0 = 1,
  allocationRatioPlanned = 1,
  accrualTime = 0L,
  accrualIntensity = NA_real_,
  piecewiseSurvivalTime = 0L,
  stratumFraction = 1L,
  kappa1 = NA_real_,
  kappa2 = NA_real_,
  lambda1 = NA_real_,
  lambda2 = NA_real_,
  gamma1 = 0L,
  gamma2 = 0L,
  accrualDuration = NA_real_,
  followupTime = NA_real_,
  fixedFollowup = 0L,
  nullVariance = 0L
)

Arguments

time

The calendar time for data cut.

rateRatioH0

Rate ratio under the null hypothesis.

allocationRatioPlanned

Allocation ratio for the active treatment versus control. Defaults to 1 for equal randomization.

accrualTime

A vector that specifies the starting time of piecewise Poisson enrollment time intervals. Must start with 0, e.g., c(0, 3) breaks the time axis into 2 accrual intervals: [0, 3) and [3, Inf).

accrualIntensity

A vector of accrual intensities. One for each accrual time interval.

piecewiseSurvivalTime

A vector that specifies the starting time of piecewise exponential survival time intervals. Must start with 0, e.g., c(0, 6) breaks the time axis into 2 event intervals: [0, 6) and [6, Inf). Defaults to 0 for exponential distribution.

stratumFraction

A vector of stratum fractions that sum to 1. Defaults to 1 for no stratification.

kappa1

The dispersion parameter (reciprocal of the shape parameter of the gamma mixing distribution) for the active treatment group by stratum.

kappa2

The dispersion parameter (reciprocal of the shape parameter of the gamma mixing distribution) for the control group by stratum.

lambda1

The rate parameter of the negative binomial distribution for the active treatment group by stratum.

lambda2

The rate parameter of the negative binomial distribution for the control group by stratum.

gamma1

The hazard rate for exponential dropout, a vector of hazard rates for piecewise exponential dropout applicable for all strata, or a vector of hazard rates for dropout in each analysis time interval by stratum for the active treatment group.

gamma2

The hazard rate for exponential dropout, a vector of hazard rates for piecewise exponential dropout applicable for all strata, or a vector of hazard rates for dropout in each analysis time interval by stratum for the control group.

accrualDuration

Duration of the enrollment period.

followupTime

Follow-up time for the last enrolled subject.

fixedFollowup

Whether a fixed follow-up design is used. Defaults to 0 for variable follow-up.

nullVariance

Whether to calculate the variance for log rate ratio under the null hypothesis.

Value

A list with two components:

Author(s)

Kaifeng Lu, kaifenglu@gmail.com

Examples

# Example 1: Variable follow-up design

nbstat1(time = 2,
       accrualIntensity = 1956/1.25,
       kappa1 = 5,
       kappa2 = 5,
       lambda1 = 0.7*0.125,
       lambda2 = 0.125,
       gamma1 = 0,
       gamma2 = 0,
       accrualDuration = 1.25,
       followupTime = 2.75)

# Example 2: Fixed follow-up design

nbstat1(time = 1.8,
       accrualIntensity = 220/1.5,
       stratumFraction = c(0.2, 0.8),
       kappa1 = 3,
       kappa2 = 3,
       lambda1 = c(0.5*8.4, 0.7*10.2),
       lambda2 = c(8.4, 10.2),
       gamma1 = 0.05,
       gamma2 = 0.05,
       accrualDuration = 1.5,
       followupTime = 0.5,
       fixedFollowup = 1,
       nullVariance = 1)


[Package lrstat version 0.2.9 Index]