issue {randomizeR} | R Documentation |
Assessment criteria for clinical trials
Description
Summarizes the criteria for the assessment of randomization procedures.
Details
Randomization in clinical trials is supposed to
control certain properties in clinical trials. In the randomizeR package,
these properties are called issues
.
It is crucial to decide which of the issues is relevant in the present
clinical trial, because a randomization procedure that manages well one issue
might behave very badly for another. The issues include
-
Selection bias can occur if future treatment allocations are predictable due to restricted randomization and unmasking of past treatment assignments. The influence of selection bias on the test decision is represented by the
selBias
class. The measure for the predictability of a randomization procedure is implemented in thecorGuess
class representing the expected number of correct guesses. -
Chronological bias can occur if a time trend is present in the data. Time trends occur due to learning curves, relaxed inclusion/ exclusion criteria or new co-medication. Chronological bias is represented by the
chronBias
class. -
Additive combination of chronological and selection bias may occur if a time trend and selection bias are present in the data. The combined bias is represented by the
combineBias
class. -
Balance is important in order to ensure proper power estimation properties of the treatments. However, a high degree of balance favors selection bias. Depending on the clinical context, a randomization procedure should be chosen that admits a suitable imbalance. Imbalance bias is represented by the
imbal
class. The power loss due to imbalance can be assessed directly via thesetPower
class
See Also
Representation of randomization procedures: randPar
Generation of randomization sequences: genSeq
Assessment of randomization sequences: assess
Comparison of randomization sequences: compare
Other issues:
chronBias
,
combineBias()
,
corGuess
,
imbal
,
selBias
,
setPower()