Sample size calculation and subgrouping according to age
The number of healthy controls who were enrolled in the parent study was
100. All 100 controls were included as study participants in the current
study. Using the power command in Stata, we conducted a one-sample
correlation test to estimate the minimum sample required to detect a
correlation of a least r=0.3 between RALS and age. The minimum sample
size required was 100. All participants were subdivided into three age
groups (Group 1:18−29 years, Group 2: 30−39 years, Group 3: 40-49 years
and Group 4: 50-70 years).