Patient records from two hospitals were reviewed and assigned a ranking score designed to measure the level of hospital care. The scores from 15 patients were used to test the hypothesis whether the two groups (hospital_1, hospital_2) differ significantly with respect to hospital care. The output from Stata is given below

hospital Obs Rank sum Expected 15 317 232.5 15 148 232.5 Combined 30 465 465 Unadjusted variance 581. 25 Adjustment for ties -1.94 Adjusted variance 579. 31 HO: scores (hospital==1) = scores (hospital==2) Z = 3.511 Prob > |z| = 0.0004 Exact prob = 0.0002