imbal function

Representing the allocation imbalance

Represents the imbalance of the treatment assignments of patients in a clinical trial.

imbal(type)

Arguments

• type: character string, should be one of "imb", "absImb", "loss", or "maxImb", see Details.

Returns

S4 object of class imbal, a formal representation of the issue of imbalance in a clinical trial.

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

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()