Representing Wei's Urn Design
Represents Wei's Urn Design.
udPar(N, ini, add, groups = LETTERS[1:2])
N |
integer for the total sample size of the trial. |
ini |
integer representing the initial urn composition. |
add |
integer representing the number of balls that are added to the urn in each step. |
groups |
character vector of labels for the different treatments. |
An urn is filled with a number of ini balls of both of the treatments.
Afterwards, a ball is drawn randomly from the urn. Finally, add balls
are added to the urn from the opposite treatment. This procedure is repeated until
N patients are assigned.
S4 object of the class udPar.
L.J. Wei (1977) A Class of Designs for Sequential Clinical Trials. Journal of the American Statistical Association, 72, 382-6.
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