Represents the imbalance of the treatment assignments
of patients in a clinical trial.
Usage
imbal(type)
Arguments
type
character string, should be one of "imb", "absImb",
"loss", or "maxImb", see Details.
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
Value
S4 object of class imbal, a formal represenation of the issue of
imbalance in a clinical trial.
References
A.C. Atkinson (2014) Selecting a biased coin design. Statistical Science, 29, Vol. 1, 144-163.
See Also
Other issues: chronBias,
combineBias, corGuess,
issue, selBias,
setPower