Fig. 3From: Duplicate analysis method: a cheaper alternative to commercial IQC materials in limited resource settings for monitoring CD4 testingBland–Altman bias plots for the CD4 values obtained on day 1 and day 2. The figure shows the Bland Altman plots for the duplicate analysis method using samples with normal (a) and low (b) CD4 counts. The X axis shows the average between the values obtained on both the days and the Y axis shows the differences between the values obtained on the 2 days. The mean differences in CD4 counts, the lower limits of agreement (mean −2 SD), and the upper limits of agreement (mean +2 SD) are displayed as horizontal lines.Back to article page