Table 1.

Descriptive statistics for the components of SICCT after quality control

	Min	Median	Max	Mean	Var	SD
a 1	1	6	16	6.17	2.33	1.53
a 2	0	6	50	6.83	6.31	2.51
b 1	1	6	16	6.19	2.33	1.53
b 2	0	6	90	6.97	10.46	3.23
da	−7	0	43	0.66	3.54	1.88
db	−7	0	81	0.78	7.53	2.74
dc	−43	0	81	0.12	5.72	2.39

Descriptive statistics for the four skin thickness measurements, before (a ₁ and b ₁), and after (a ₂ and b ₂) inoculation of the tuberculins, and for the derived traits da = a ₂ − a ₁, db = b ₂ − b ₁, and the skin test dc = db − da following quality control