Table 3 Indicators of infant illness severity and infant nurse staffing for duration of unit stay by unit organisational type .

	Birthweight mean (SD)	Gestation mean (SD)	Predicted mortality score median (IQ range)	Registered nurses median (IQ range)	Nurse provision ratio median (IQ range)	Specialist nurse provision ratio median (IQ range)
Cohort	1231.7 (359)	29.3 (2.6)	0.98 (0.08)	4.6 (2.5)	0.92 (2.5)	1.35 (0.6)
Unit volume type
High	1176.4 (344)	29 (2.6)	0.98 (0.12)	6 (1.1)	0.93 (0.21)	1.41 (0.47)
Medium	1257.3 (356)	29.3 (2.5)	0.99 (0.06)	4.3 (2.3)	0.94 (0.22)	1.33 (0.75)
Low	1270.5 (373)	29.5 (2.5)	0.99 (0.06)	3.5 (1.4)	0.87 (0.23)	1.26 (0.63)
	p⩽0.01*	p⩽0.01*	p⩽0.01°	p⩽0.001°	p⩽0.001°	P⩽0.001°
Unit consultant availability
High	1228.9 (351)	29.2 (2.6)	0.99 (0.05)	5.5 (2.6)	0.94 (0.22)	1.35 (0.62)
Low	1234.6 (368)	29.3 (2.6)	0.98 (0.08)	4 (2.2)	0.89 (0.25)	1.35 (0.58)
	p = 0.69*	p = 0.82*	p = 0.29†	p⩽0.001†	p⩽0.001†	p = 0.42†
Unit nursing establishment
High	1230 (355)	29.3 (2.6)	0.99 (0.08)	4.8 (2.8)	0.95 (0.21)	1.32 (0.55)
Low	1234 (364)	29.3 (2.6)	0.98 (0.09)	4.4 (2.2)	0.87 (0.21)	1.39 (0.67)
	p = 0.78*	p = 0.72*	p = 0.83†	p⩽0.001†	p⩽0.001†	p⩽0.01†

Statistical tests: *one way ANOVA, °Kruskal Wallis, †Mann Whitney U test