Table 5.

Variability in quantitative results under the same and different conditions

	Analysis	No. of Valid Comparisons	Mean of Difference of Repeat Tests in IU/ml (95% CI)	Within-Subject SD of Variation in IU/ml (95% CI)	Coefficient of Variation (%)
Identical conditions, same sample	All values	739	0.01 (−0.01 to 0.04)	±0.24 (0.23–0.25)	13
	Group with baseline < 0.1	250	0.02 (0.01 to 0.03)	±0.06 (0.06–0.07)	263
	Group with baseline 0.1–0.25	77	0.02 (−0.03 to 0.08)	±0.17 (0.15–0.20)	99
	Group with baseline 0.25–0.8	148	−0.002 (−0.03 to 0.03)	±0.13 (0.12–0.15)	30
Repeat over times	All values	932	−0.18 (−0.23 to −0.13)	±0.69 (0.66 –0.72)	60
	Group with baseline < 0.1	134	0.04 (0.01 to 0.07)	±0.31 (0.29–0.33)	588
	Group with baseline 0.1–0.25	21	0.01 (−0.09 to 0.1)	±0.28 (0.21–0.37)	151
	Group with baseline 0.25–0.8	418	−0.11 (−0.15 to −0.08)	±0.36 (0.34–0.38)	84

Data for all analyses included only the first and second valid comparisons.