Table I.

Summary data (reciprocals of titre end-points) from a comparison of three techniques (Aggl: standard tube test; ELAT-W: enzyme-linked antiglobulin test; ELAT-G: like ELAT-W but with gradient centrifugation instead of washing) for the indirect antiglobulin test. Three summary statistics are presented: arithmetic mean, median and geometric mean (GM). The geometric mean has the most preferable properties. (Q₁-Q₃: interquartile range; SD: standard deviation; GSD: geometric standard deviation).

Antibody	Technique
	Aggl	ELAT-W	ELAT-G
1	32	512	128
2	32	256	128
3	32	64	128
4	32	64	128
5	32	64	128
6	8	64	32
7	32	32	128
8	16	32	64
9	8	16	64
10	64	16	128
11	8	8	256
12	4	8	16
13	4	8	32
14	4	8	32
15	4	8	2
Mean (±1SD)	21 (3 – 38)	77 (−58 – 213)	93 (26 – 160)
Median (Q1-Q3)	16 (4 – 32)	32 (8 – 64)	128 (32 – 128)
GM (±1GSD)	14 (5 – 37)	31 (8 – 115)	61 (18 – 206)