Table 3. Percentage (95% CIs) of records classified as missed matches compared with reference standard following deterministic and probabilistic data linkage.

	Records from 1998 to 2003 (n = 99,220)		Records from 2004 to 2009 (n = 128,666)		Records from 2010 to 2015 (n = 189,373)
	Deterministic	Probabilistic	Deterministic	Probabilistic	Deterministic	Probabilistic
Links	58,768	62,941	100,282	101,086	153,226	153,547
Specificity %	0.985	0.981	0.987	0.996	0.998	0.997
Sensitivity %	0.914	0.976	0.993	0.994	0.997	0.999
Missed match %	8.6 (8.4, 8.8)	2.4 (2.2, 2.5)	1.3 (1.2, 1.3)	0.4 (0.4, 0.5)	0.4 (0.3, 0.4)	0.1 (0.1, 0.1)
Age
0–3	12.1 (11.8, 12.5)	3.2 (3.1, 3.4)	1.4 (1.3, 1.4)	0.4 (0.3, 0.4)	0.2 (0.2, 0.3)	0.0 (0.0, 0.1)
4–7	3.8 (3.4, 4.1)	1.3 (1.1, 1.5)	1.7 (1.5, 2.0)	0.8 (0.6, 1.0)	0.4 (0.3, 0.5)	0.2 (0.1, 0.2)
8–11	2.2 (1.9, 2.4)	0.6 (0.4, 0.7)	1.7 (1.5, 2.0)	0.7 (0.5, 0.9)	0.3 (0.2, 0.4)	0.1 (0.0, 0.1)
12–15			0.7 (0.5, 0.8)	0.2 (0.1, 0.3)	0.8 (0.7, 1.0)	0.5 (0.4, 0.6)
16–19			0.6 (0.5, 0.7)	0.1 (0.0, 0.2)	0.6 (0.5, 0.7)	0.3 (0.2, 0.3)
20–23					0.2 (0.2, 0.3)	0.1 (0.0, 0.1)
Sex
Missing	100.0 (all missed)	21.0 (14.6, 26.5)	100.0 (all missed)	40.0 (9.6, 58.3)	100.0 (all missed)	16.7 (1.8, 21.9)
Male	8.6 (8.3, 9.0)	2.4 (2.3, 2.6)	1.3 (1.2, 1.4)	0.4 (0.3, 0.5)	0.3 (0.3, 0.3)	0.1 (0.1, 0.1)
Female	8.2 (7.9, 8.5)	2.2 (2.1, 2.4)	1.3 (1.2, 1.4)	0.4 (0.4, 0.5)	0.4 (0.3, 0.4)	0.1 (0.1, 0.2)
Ethnic group
Missing	10.4 (10.1, 10.8)	2.7 (2.6, 2.9)	2.2 (2.0, 2.4)	0.6 (0.5, 0.7)	0.9 (0.7, 1.0)	0.2 (0.1, 0.3)
White	6.8 (6.5, 7.1)	2.0 (1.8, 2.1)	1.0 (0.9, 1.0)	0.4 (0.3, 0.4)	0.3 (0.2, 0.3)	0.1 (0.1, 0.1)
Mixed	3.7 (0.1, 4.4)	0.9 (-0.9, 1.8)	1.0 (0.6, 1.3)	0.3 (0.1, 0.4)	0.2 (0.1, 0.3)	0.2 (0.1, 0.3)
Asian	7.0 (6.0, 8.0)	2.2 (1.6, 2.6)	1.0 (0.8, 1.2)	0.3 (0.2, 0.4)	0.6 (0.4, 0.7)	0.2 (0.1, 0.2)
Black	7.0 (5.5, 8.3)	2.3 (1.4, 2.9)	1.4 (1.0, 1.7)	0.4 (0.2, 0.6)	0.4 (0.2, 0.5)	0.1 (0.0, 0.2)
Chinese/Other	11.7 (10.1, 13.2)	2.7 (1.8, 3.3)	4.4 (3.5, 5.3)	0.6 (0.3, 0.9)	0.9 (0.6, 1.1)	0.1 (0.0, 0.2)
Socio-economic group
Missing	26.4 (25.2, 27.6)	4.3 (3.8, 4.9)	1.7 (1.5, 1.8)	0.5 (0.4, 0.6)	0.2 (0.1, 0.2)	0.1 (0.0, 0.1)
Low deprivation	7.1 (6.8, 7.3)	2.2 (2.1, 2.4)	1.0 (0.9, 1.1)	0.4 (0.3, 0.4)	0.3 (0.2, 0.3)	0.1 (0.1, 0.1)
High deprivation	6.8 (6.4, 7.1)	2.2 (2.0, 2.4)	1.1 (1.0, 1.3)	0.5 (0.4, 0.5)	0.3 (0.2, 0.3)	0.2 (0.1, 0.2)
Foreign	69.4 (61.2, 78.1)		66.3 (59.8, 73.1)	1.5 (-0.2, 3.2)	31.6 (27.7, 35.4)	0.8 (0.0, 0.9)
No fixed abode			8.7 (2.0, 12.0)	0.0 (none missed)

Note. Number of records in each category shown in Table 6