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Table 4 Total sample size needed to detect a 10 to 20 % difference between two groups in the geometric mean of the percentage change in ACR under different scenarios

From: Consecutive first-morning urine samples to measure change in the albumin-to-creatinine ratio: a pilot study of a home urine collection protocol

   Minimum detectable difference between groups
Number of urine samples at each time point (baseline and follow-up) Log-scale standard deviationa 10 % 15 % 20 %
One sample 0.59 984 414 220
Average of two consecutive samples 0.49 678 286 152
Average of three consecutive samples 0.50 706 298 158
  1. Based on a type I error of 5 % and power of 80 %
  2. aStandard deviation of the log-transformed percentage change in the albumin-to-creatinine ratio between baseline and 3-month follow-up