A S4 object representing
an exponentially distributed endpoint in a clinical trial.
Arguments
lambda
vector of the exponential rate parameters in each treatment group.
cenRate
exponential censoring rate in a survival study.
accrualTime
duration of the accrual period in a survival study.
cenTime
total duration of a survival study (maximum length of followup).
Details
The expEnd function is a constructor function
for an S4 object of the class expEnd representing
an exponentially distributed endpoint in a clinical trial.
In conjunction with the assess function, exponential endpoints
admit the calculation of the 'exact' type-I-error probability and power
using an approximation formula.