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Table 5 Summary of observations from the four-treatment case

From: Investigating the relationship between predictability and imbalance in minimisation: a simulation study

  Predictability at P= 1.0, % Na Recommended P-value Predictability at this P-value, % Reduction in predictability, % P-value at which imbalance occurs
One variable
Two categories (equal prevalence) 24 to 25 100 0.7b 24 0 0.6
   ≥200 0.7 b 25 0 -
Two variables
Both with 2 categories (equal prevalence) 45 100 0.9 44 1 0.8
   200 0.7 41 4 0.6
   ≥300 0.7 41 4 -
Three variables
All with 2 categories (equal prevalence) 58 100 1.0 58 0 1.0
   200 0.7 49 9 0.6
   300 0.7 49 9 0.5
   ≥400 0.7 49 9 -
Four variables
All with 2 categories (equal prevalence) 67 100 1.0 67 0 1.0
   200 0.8 59 8 0.7
   300 0.7 53 14 0.5
   ≥400 0.7 53 14 -
  1. aThe categories of N are dependent upon the point at which imbalance is observed (the value of probability of assignment P). bFor one prognostic variable the reduction in predictability is so small as the probability of assignment P is reduced that the recommended P- value is 1.0.