Table 1.

Measures of random and systematic error for red blood cell distribution width, C-reactive protein, 25 hydroxyvitamin D, body mass index and pack-years of smoking for illustrative examples

UK Biobank field number	Description	Sample size	Accuracy coefficienta	Intraclass correlation coefficientb (95% CI)	Correction factorc, $\widehat{\lambda }$	Var($\widehat{\lambda }$)	Var(1/$\widehat{\lambda }$)
30070	Red blood cell distribution width	18 379	1.00	0.52 (0.51, 0.53)	1.9356	0.000410	0.000029
30710	C-reactive protein	16 549	1.00	0.29 (0.27, 0.30)	3.4987	0.007635	0.000051
30890	25 hydroxyvitamin D	15 435	0.99	0.55 (0.54, 0.56)	1.8091	0.000335	0.000031
21001	Body mass index	20 257	1.00	0.93 (0.92, 0.93)	1.0794	0.000001	0.000001
20161	Pack-years of smoking	4744	1.00	0.85 (0.84, 0.86)	1.1745	0.000030	0.000016

^aAccuracy coefficient is a measure of systematic error between two measures.

^bIntraclass correlation coefficient is a measure of overall agreement between two measures.

^cCorrection factor ($\widehat{\lambda }$) is the reciprocal of the intraclass correlation coefficient.