. Author manuscript; available in PMC: 2014 Jul 16.

Published in final edited form as: Cytometry B Clin Cytom. 2007 Jul;72(4):249–255. doi: 10.1002/cyto.b.20176

Table 2.

CD8 Cell Percentages Obtained by the Four MACS Laboratories during the Study Period, Compared with the Median for Reporting Laboratories Participating in the IQA

	IQA	Site 1	Site 2	Site 3	Site 4
Time period A
Number of specimens^a	23	23	23	23	23
Mean	50.7	50.0	50.2	52.1	48.7
Median	52	51	51	53	50
95% CI Upper	55.5	54.5	54.6	56.5	52.8
95% CI Lower	46.3	45.6	45.8	47.8	44.5
P value^b		0.080	0.058	0.006⁺	0.005⁺
Number of unacceptable results^c		0	0	1	6
Time period B
Number of specimens	23	23	23	23	23
Mean	50.6	50.3	49.8	50.3	50.3
Median	51	52	50	51	52
95% CI Upper	55.2	55.0	54.3	54.5	55.1
95% CI Lower	45.9	45.7	45.3	46.0	45.5
P value^b		0.629	0.60	0.267	0.444
Number of unacceptable results^c		0	0	1	0

Time period A, when sites 1 and 2 used 3-color and sites 3 and 4 used 2-color, and time period B, when all sites used 3-color.

Only specimens analyzed at all four laboratories (23/66) were included in this analysis.

P-value by Wilcoxon Sign Rank test comparing each site with the IQA, Significance set at P < 0.0125 after Bonferroni correction for multiple comparisons.

Values that differed from the IQA median by 5% or more.