Table 5. Percent of Medicare patients in unprofitable diagnosis-related groups, by type of hospital and measure of unprofitability: United States, 1985.

Measure of unprofitability	Last- resort hospitals	Other hospitals	Difference1	Z- statistic2	Difference of difference3	Z- statistic
	Percent			Percent
All unprofitable cases	2.265	2.055	0.210	1.58	0.387	2.28
Mean loss per case of more than $100	1.100	1.169	−0.069	—	−0.026	—
Mean loss per case of more than $200	0.447	0.421	−0.026	—	−0.036	—

¹Calculated as shown in following example: 0.210 = 2.265 − 2.055.

²Result of test of null hypothesis that the difference and the difference of difference are zero using the normal approximation to the binomial. Under the null hypothesis, a value of 1.96 or greater would arise by chance only 5 percent of the time; a statistic of 2.57 or greater would arise only 1 percent of the time (2-tailed tests).

³Using 1981 as control. Calculated as shown in following example: 0.387 = (2.265 − 2.055) − (1.349 − 1.526).

NOTES: Last-resort hospitals are generally city and county hospitals in cities of 1 million population or more; the remainder of the hospitals in these cities are designated “other.” Data from waiver States are excluded. Figures are based on a 5-percent sample of cases.

SOURCE: Health Care Financing Administration, Bureau of Data Management and Strategy: Data from the Medicare Provider Analysis and Review (MEDPAR) file and Medicare cost reports.