Assessing the agreement of biomarker data in the presence of left-censoring

BMC Nephrology

Table 3 Simulation results based on 1000 data sets with sample size of 50 -- Per cent censoring (25%, 25%)

Per cent censoring	True ρ	True ρ _c	Method	Mean ${\hat{ρ}}_{c}$	Relative bias (%)	Empirical SD	Mean SE	The percentage of 95% confidence intervals that include true value of CCC
(25%, 25%)	0.25	0.238	1. Delete the pair	0.1402	−41.09	0.1693	0.1486	87.1
			2. Replace by LOD	0.2079	−12.65	0.1509	0.1172	88.2
			3. Replace by 0.5 × LOD	0.1811	−23.91	0.2088	0.1163	83.8
			4. Replace by c × LOD	0.1949	−18.09	0.1813	0.1162	83.9
			5. ML	0.2310	−2.94	0.1351	0.1304	92.7
	0.50	0.476	1. Delete the pair	0.2936	−38.32	0.1481	0.1386	79.4
			2. Replace by LOD	0.4144	−12.94	0.4115	0.1016	87.3
			3. Replace by 0.5 × LOD	0.3661	−23.09	0.1854	0.1024	79.4
			4. Replace by c × LOD	0.3722	−21.81	0.1770	0.1026	81.2
			5. ML	0.4636	−2.61	0.1151	0.1095	93.4
	0.75	0.714	1. Delete the pair	0.5169	−27.61	0.1341	0.1071	66.7
			2. Replace by LOD	0.6429	−9.96	0.1438	0.0694	88.3
			3. Replace by 0.5 × LOD	0.5812	−18.60	0.2127	0.0720	78.5
			4. Replace by c × LOD	0.5909	−17.24	0.1917	0.0727	79.6
			5. ML	0.7025	−1.61	0.0759	0.0716	93.6

Abbreviations: LLD Lower Limit of Detection; ML Maximum Likelihood, C = Random number from uniform distribution (0, 1), CI confidence interval, Relative bias = $\frac{(Mean {\hat{ρ}}_{c} - True ρ_{c})}{True ρ_{c}} \times 100 %$ CCC⁵= $ρ_{c} = \frac{2 COV (X, Y)}{VAR (X) + VAR (Y) + {(E (X) - E (Y))}^{2}}$ .

ISSN: 1471-2369