Calculate operating characteristics for predictive probability method.
It is assumed that the true response rate is truep
. Trials can stop for Futility
or Efficacy. Trials can also stop at Interim or Final for Futility or Efficacy.
There are two variations of decision rule, Decision 1 and Decision 2, to
evaluate decision at Interim or Final, for Futility or Efficacy. Decision 1 is
used when decision1 == TRUE
which is the default setting.
Decision 1:
The criteria for Decision 1 for Interim looks are :
interim GO = P(successful trial at final) > phiU
interim STOP = P(successful trial at final) < phiL
The criteria for Decision 1 for Final looks are:
Final GO = P( response rate > p0 | data) > tT
Final STOP = P( response rate > p0 | data ) < tT
Usage
ocPredprob(
nnE,
truep,
p0,
phiU,
p1 = p0,
tT = 1 - tF,
tF = 1 - tT,
phiL = 1 - phiFu,
phiFu = 1 - phiL,
parE = c(1, 1),
sim = 50000,
wiggle = FALSE,
nnF = nnE,
decision1 = TRUE
)
Arguments
- nnE
(
numeric
):
sample size or sizes where study can be stopped for Efficacy decision. If0
orNULL
andlength(nnE) = 1
then no Efficacy looks are performed.- truep
(
number
):
assumed true response rate or true rate (scenario).- p0
(
number
):
lower Futility threshold of response rate.- phiU
(
number
):
upper threshold on the predictive probability.- p1
(
number
):
upper Futility threshold of response rate.- tT
(
number
):
threshold of which assumedtruep
exceeds acceptable threshold ofp0
.- tF
(
number
):
threshold of which assumedtruep
does not exceed threshold ofp1
.- phiL
(
number
):
lower threshold on the predictive probability.- phiFu
(
number
):
upper threshold on the predictive probability.- parE
(
numeric
):
alpha and beta parameters for the prior on the treatment population. Default set at alpha = 1, beta = 1, or uniform prior.- sim
(
number
):
number of simulations.- wiggle
(
flag
):
generate random look locations (not default). Ifwiggle = TRUE
andnnE = nnF
, then all wiggled looks are the same betweennnE
andnnF
.- nnF
(
numeric
):
sample size or sizes where study can be stopped for Efficacy decision. If0
orNULL
andlength(nnF) = 1
then no Futility looks are performed.- decision1
(
flag
):
Flag ifdecision1 = TRUE
then Decision 1 rules will be used, otherwise Decision 2 rules will be used.
Value
A list with the following elements:
oc
: matrix with operating characteristics with the following details:ExpectedN
: expected number of patients in the trialsPrStopEarly
: probability to stop the trial early (before reaching the maximum sample size)PrEarlyEff
: probability of Early Go decisionPrEarlyFut
: probability of for Early Stop decisionPrEfficacy
: probability of Go decisionPrFutility
: probability of Stop decisionPrGrayZone
: probability between Go and Stop ,"Evaluate" or Gray decision zone
Decision
: numeric of results withTRUE
as Go decision,FALSE
as Stop andNA
as gray zone.SampleSize
: numeric of sample sizes fromnnE
ornnF
or both.wiggled_nnE
: user input fornnE
with random distance applied.wiggled_nnF
: user input fornnF
with random distance applied.wiggled_dist
: magnitude of random distance applied in order of input looks.params
: all user input arguments.