TABLE 1.

Variability summary

Laboratory	Sample	Geometric mean (U/ml)	CV (%)	Pairs differing by twofold or more
				Predicted frequency (p[2])	No.
					Predicted	Observed
A	10	0.2	51.9	0.315	33	32
	11	0.2	34.4	0.143	13	10
	16	1.2	11.8	0.000	0	0
	4	1.4	14.3	0.001	0	0
	12	3.2	19.6	0.012	1	0
	18	4.2	15.6	0.002	0	0
	2	6.2	15.7	0.002	0	0
	1	13.0	11.0	0.000	0	0
	17	15.3	12.0	0.000	0	0
	8	15.7	12.8	0.000	0	0
	19	18.3	8.1	0.000	0	0
	3	18.4	9.5	0.000	0	0
	7	18.8	10.0	0.000	0	0
	14	24.6	10.4	0.000	0	0
	21	26.4	10.7	0.000	0	0
	13	26.9	9.4	0.000	0	0
	6	29.8	12.8	0.000	0	0
	20	51.4	17.0	0.004	0	0
	15	73.0	11.2	0.000	0	0
	9	253.5	15.7	0.002	0	0
	5	1,133.8	18.7	0.008	1	0
B	10	4.0	0.0	0.000	0	0
	11	4.8	53.9	0.332	35	36
	18	6.0	39.1	0.193	20	56
	4	6.4	69.7	0.436	46	54
	16	8.3	53.4	0.328	34	54
	12	19.3	35.2	0.151	16	10
	8	19.7	28.7	0.081	9	6
	2	21.7	52.2	0.318	33	29
	21	21.9	21.3	0.020	2	1
	17	23.2	21.1	0.019	2	5
	13	33.5	37.7	0.179	19	18
	3	38.7	29.2	0.087	9	4
	19	41.8	25.6	0.052	5	2
	1	42.8	41.2	0.215	23	22
	6	44.8	40.2	0.206	22	31
	7	45.4	38.2	0.185	19	19
	20	48.4	30.5	0.101	11	7
	14	68.1	40.3	0.206	22	18
	15	83.7	19.9	0.013	1	1
	9	348.7	27.9	0.073	8	4
	5	1,450.9	21.9	0.023	2	2