Multivariate statistical analysis: a brief introduction.

Antibody titre Zero 39 (26.5%) 17 (20.5%) 50 (41.3%) 47 (43.1%) Trace 45 (30.6%) 29 (34.9%) 38 (31.4%) 30 (27.5%) >1 in 16 63 (42.9%) 37 (44.6%) 33 (27.3%) 32 (29.4%)