Definition and calculation of components of within population-variability in RNA viral load and CD4 cell count during untreated HIV-1 infection in adults.

*Samples with RNA>500 copies/mL only. The 95% confidence interval was calculated based on the reported standard deviation among 6 visits, of 0.264 log10 copies/mL, applying a Student T-statistic for 5 degrees of freedom.$Lacking a reported standard deviation, the 95% confidence interval was estimated by multiplying the reported full ( = 119 cells/��L) CD4 range among 6 visits with the ratio of 95% range to full range ( = 5,392/6,563 copies/mL) in RNA.#For a normal distribution, the 95% confidence interval is equal to the interquartile range divided by 0.675. As population median value, we here take the median across all studies shown in Figure 2.+Average within-population variability was taken from the pool of eligible studies depicted in Figure 1, as the sample in [32] was too small to provide a representative estimate of typical within-population variability.