Table 1

Observed vs expected mortality and length of stay during the control and intervention periods and comparisons between the two using the Wilcoxon Mann-Whitney U test

	Control (n=12 months)	Intervention (n=9 months)	% Improvement	P value	Cohen’s d
	Mean (SD)	Mean (SD)	% Improvement	P value	Cohen’s d
Mortality O/E**	1.14 (0.14)	1.00 (0.18)	12	0.09	0.87
Arithmetic LOS O/E††	1.54 (0.05)	1.47 (0.05)	4.5	0.004	1.40
Geometric LOS O/E††	1.25 (0.04)	1.17 (0.04)	6.5	0.001	2.00

*Based on data from 11 132 patient admissions for control months and 8346 for intervention months.
†Based on data from 11 101 patient admissions for control months and 8313 for intervention months.
LOS, length of stay; O/E, observed versus expected values.