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Represents the imbalance of the treatment assignments of patients in a clinical trial.
imbal(type)S4 object of class imbal, a formal representation of the issue of
imbalance in a clinical trial.
character string, should be one of "imb", "absImb",
"loss", or "maxImb", see Details.
Balance of the treatment assignment of patients can
be an issue in the design of a clinical trial. The imbal function is
a constructor function for an S4 object of class imbal representing
the issue of imbalance of a clinical trial. The parameter type can
take the following values:
The type
"imb"the final imbalance, i.e. difference in group sizes at the end of a trial
"absImb"the absolute value of the final imbalance
"loss"the loss in power estimation, i.e. imb^2/N
"maxImb"the maximal attained imbalance during the trial
A.C. Atkinson (2014) Selecting a biased coin design. Statistical Science, 29, Vol. 1, 144-163.
Other issues:
chronBias,
combineBias(),
corGuess,
issue,
selBias,
setPower()