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Table 2 Simulated preliminary data for power and sample size calculations

From: Sample size and power determination when limited preliminary information is available

Variable   Estimated correlation coefficient
0.50 0.80 0.90
N Mean STDa Mean STDa Mean STDa
The simulated MRI breast density at baseline data 10,000 22.1 2.59 22.1 2.59 22.1 2.59
The simulated MRI breast density at follow-up data 10,000 16.3 3.33 16.3 3.32 16.3 3.32
 pre_ctH2O: Predicted mean and STD for 2nd simulation 5,000,000 23.8 1.53 23.8 1.53 23.8 1.53
 post_ctH2O: Predicted mean and STD for 2nd simulation 5,000,000 21.3 1.64 21.3 1.64 21.4 1.63
Random selected baseline water data after applying the regression model 5,000,000 23.9 2.16 23.9 2.16 23.9 2.16
Random selected follow-up water data after applying the regression model 5,000,000 21.3 2.32 21.3 2.32 21.4 2.31
Water: Follow-up data – Baseline data b 5,000,000 -2.5 2.12 −2.5 1.42 −2.5 1.09
 pre_ctHHb: Predicted mean and STD for 2nd simulation 5,000,000 5.2 0.19 5.2 0.19 5.2 0.19
 post_ctHHb: Predicted mean and STD for 2nd simulation 5,000,000 4.8 0.23 4.8 0.23 4.9 0.23
Random selected baseline ctHHb data after applying the regression model 5,000,000 5.2 0.26 5.2 0.26 5.2 0.26
Random selected follow-up ctHHb data after applying the regression model 5,000,000 4.8 0.32 4.9 0.32 4.9 0.32
ctHHb: Follow-up data – Baseline data b 5,000,000 −0.3 0.29 −0.3 0.20 −0.3 0.16
 pre_Lipid: Predicted mean and STD for 2nd simulation 5,000,000 66.3 2.06 66.3 2.06 66.3 2.06
 post_Lipid: Predicted mean and STD for 2nd simulation 5,000,000 68.9 2.01 68.9 2.00 68.9 2.00
Random selected baseline Lipid data after applying the regression model 5,000,000 66.3 2.92 66.3 2.92 66.3 2.92
Random selected follow-up Lipid data after applying the regression model 5,000,000 68.9 2.84 68.9 2.84 68.9 2.83
Lipid: Follow-up data – Baseline data b 5,000,000 2.6 2.63 2.6 1.82 2.6 1.44
  1. a STD standard deviation
  2. bThe italic font indicates that the values were used in the sample size deteremination procedure