Generation of allocation sequences in randomised trials: chance, not choice

@article{Schulz2002GenerationOA,
  title={Generation of allocation sequences in randomised trials: chance, not choice},
  author={Kenneth F. Schulz and David A. Grimes},
  journal={The Lancet},
  year={2002},
  volume={359},
  pages={515-519}
}

Random allocation in controlled clinical trials: a review.

  • B. Egbewale
  • Medicine
    Journal of pharmacy & pharmaceutical sciences : a publication of the Canadian Society for Pharmaceutical Sciences, Societe canadienne des sciences pharmaceutiques
  • 2014
TLDR
A review of literatures published in the Pubmed database on concepts of common allocation techniques used in controlled clinical trials found four main random allocation techniques were identified.

The Role of Random Allocation in Randomized Controlled Trials: Distinguishing Selection Bias from Baseline Imbalance

Background: This paper addresses one threat to the internal validity of a randomized controlled trial (RCT), selection bias. Many authors argue that random allocation is used to ensure baseline

Improper analysis of trials randomised using stratified blocks or minimisation

TLDR
It is shown that balancing treatment groups using stratification leads to correlation between the treatment groups, and if this correlation is ignored and an unadjusted analysis is performed, standard errors for the treatment effect will be biased upwards, resulting in 95% confidence intervals that areToo wide, type I error rates that are too low and a reduction in power.

Randomized Block Designs

TLDR
Four types of RBDs are presented: the complete blocked randomization- with and without an interaction term between the treatment and blocking factors, the balanced incomplete block randomization-, and the permuted-blocksrandomization-designs, each of which is a better fit for certain conditions that arise from the type of data analyzed.

Fundamentals of Randomization in Clinical Trial

TLDR
A brief definition of randomization plus its concise benefits in clinical trials are presented, and the processes of an accurate randomization procedure, generation of unpredictable random allocation sequence and allocation concealment are considered.

Randomization in controlled clinical trials: why the flip of a coin is so important.

...

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Proper randomization is required to generate unbiased comparison groups in controlled trials, yet the reports in these journals usually provided inadequate or unacceptable information on treatment allocation, suggesting that nonrandom manipulation of comparison groups and selective reporting of baseline comparisons may have occurred.

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  • Mathematics
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Empirical evidence is provided that inadequate methodological approaches in controlled trials, particularly those representing poor allocation concealment, are associated with bias.