Fig 2 Comparison of CD4 counts determined with three flow cytometric methods using 96 blood samples from patients with HIV with CD4 counts <400×109/l for absolute CD4 cell counts (×109/l) and 129 blood samples for CD4 cell counts as a percentage of total lymphocyte count (CD4 percentage). FACSCount CD4 percentage was obtained from FACSCount absolute CD4 counts and total lymphocyte counts from a haematological analyser. Black lines depict bias and upper and lower limits of agreement. Grey broken lines denote 95% confidence intervals for these values