commonbounds  R Documentation 
'commonbounds' determines group sequential boundaries of the wellknown O'BrienFleming and Pocock types. These can be used as guidelines for early stopping of the trial. For HaybittlePeto type boundaries, see function 'lastbound'. Note: these are NOT the alphaspending versions of these boundaries.
commonbounds(looks, t=(1:looks)/looks, t2=t, iuse="OF", alpha=0.05, sides=2)
looks 
A number of equally spaced analysis times. 
t 
a vector of analysis times, if 
t2 
the second time scale, usually in terms of amount of
accumulating information. By default, same as the
equally spaced analysis times or the analysis times corresponding to

iuse 
the type of bounds: O'BrienFleming ("OF") or Pocock ("PK") If twosided bounds are calculated, the same type will be used for each of the two boundaries. If a vector of length two is given, the two values will be used for lower and upper bounds, respectively. Details of specification are given below. 
alpha 
Type I error(s). In twosided situations, alpha can be a single value, indicating symmetric type I error control (half of alpha for each boundary). If a vector of length two is given, this corresponds to the amount allocated to the lower and upper boundaries, respectively. The total alpha must be greater than 0 and less than or equal to 1. 
sides 
Designates one or twosided bounds. 
This function calculates boundaries corresponding to traditional
O'BrienFleming or Pocock boundaries. Note that these are not the
alpha spending function versions of the boundaries. For those, use ldBounds
.
'commonbounds' returns an object of 'class' '"ldBounds"'.
For details about this object class, see the documentation for the
ldBounds
function.
Charlie Casper charlie.casper@hsc.utah.edu
Reboussin, D. M., DeMets, D. L., Kim, K. M., and Lan, K. K. G. (2000) Computations for group sequential boundaries using the LanDeMets spending function method. Controlled Clinical Trials, 21:190207.
DeMets, D. L. and Lan, K. K. G. (1995) Recent Advances in Clinical Trial Design and Analysis, Thall, P. F. (ed.). Boston: Kluwer Academic Publishers.
Lan, K. K. G. and DeMets, D. L. (1983) Discrete sequential boundaries for clinical trials. Biometrika, 70:65963.
Generic functions summary.ldBounds
and
plot.ldPower
.
ldBounds
for boundaries that use the alpha spending approach.
ldPower
for exit probabilities given boundaries OR drift
(effect) given power OR confidence interval OR adjusted pvalue.
## From Reboussin, et al. (2000)
time < seq(0.2,1,length=5)
obf.bd < commonbounds(t=time)
summary(obf.bd)
plot(obf.bd)
# Equivalent bounds to above
obf.bd2 < commonbounds(5)
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