computeBounds {GroupSeq} | R Documentation |
Function to calculate boundaries corresponding to particular type I error spending rates and times of interim analyses, see Lan & DeMets 83.
computeBounds(n, drift, alpha, phi, t, t2, OneOrTwoSidedBounds, whatSpendingFunctionIsUsed, boundsTruncation)
n |
is the number of interim analyses |
drift |
drift is the true mean of the process, the noncentrality - drift is set to zero, and so does not affect function |
alpha |
is the total type I error. |
phi |
optional Parameter referring to Power Family |
t |
is the information times. |
t2 |
is the 'second' time scale, used for the covariance of sequential statistics, usually number of events or subjects. |
OneOrTwoSidedBounds |
indicates one or two sided boundaries. |
whatSpendingFunctionIsUsed |
indicates type I error spending function. |
boundsTruncation |
is the user selected truncation on integration limits. |
lowerBounds |
the vector of lower standardized boundaries |
upperBounds |
the vector of upper standardized boundaries |
probExit |
vector of exit probabilities |
probDifference(i) |
probExit(i)-probExit(i-1) |
drift MAY NOT be changed without adding code!
This function is meant to be called in context of using groupseq
Roman Pahl
Lan & DeMets 1983 Biometrika http://www.biostat.wisc.edu/landemets/
groupseq
, alphaByUseFunction
stdDeviations
, pnorm
jointDensity
, tailProbability
,
searchForBound
## fictious example computeBounds(2,0,0.05,0,c(0.5,1.0),c(0.5,1.0),1,1,8) ##with following result: #$lowerBounds #[1] -8 -8 # #$upperBounds #[1] 2.537988 1.662070 # #$exitProbabilities #[1] 0.005574597 0.050000000 # #$differencesExitProbabilities #[1] 0.005574597 0.044425403