EXHIBIT 1.
Characteristics Of US Hospitals Before And After Matching For Analysis
| Variable | Before matching (number or mean)
|
After matching (number or mean)
|
Standardized difference in means (low versus high) (%) | ||
|---|---|---|---|---|---|
| Initial sample (n = 2,976) | Analytic sample (n = 2,826) | Low staffing (n = 1,413) | High staffing (n = 1,413) | ||
| Registered nurse hours per adjusted patient day | 6.4 | 6.5 | 5.1 | 8.0 | 164.1 |
| Balancing score | —a | —a | 7,170 | 7,170 | 0.0 |
| COVARIATES | |||||
| Number of beds | 227 | 224 | 219 | 229 | 5.3 |
| Resident/fellow physicians per bed | 0.06 | 0.05 | 0.05 | 0.06 | 5.6 |
| Operating profit margin | −0.02 | −0.02 | −0.02 | −0.02 | 0.9 |
| Percent black patients | 11.6 | 11.6 | 11.6 | 11.7 | 0.9 |
| Percent Hispanic patients | 2.3 | 2.4 | 2.4 | 2.4 | 0.5 |
| Percent Medicaid mix | 19.1 | 17.7 | 17.3 | 18.0 | 6.3 |
| Socioeconomic status indicator | −0.7 | −0.6 | −0.6 | −0.6 | 1.0 |
| Herfindahl-Hirschman Index | 772 | 766 | 802 | 729 | 4.7 |
| Technology level (number) | 3.5 | ||||
| High | 1,049 | 1,025 | 498 | 527 | |
| Low | 1,927 | 1,801 | 915 | 886 | |
| Ownership (number) | 0.4 | ||||
| For-profit | 578 | 575 | 289 | 286 | |
| Not-for-profit | 2,398 | 2,251 | 1,124 | 1,127 | |
| Geographic location (number) | 2.3 | ||||
| Urban | 2,655 | 2,548 | 1,280 | 1,268 | |
| Rural | 321 | 278 | 133 | 145 | |
| Skilled nursing facility (number) | 4.5 | ||||
| Yes | 485 | 360 | 167 | 193 | |
| No | 2,491 | 2,466 | 1,246 | 1,220 | |
SOURCE Authors’ analysis of data from all 2,976 hospitals with data and analytic sample of 2,826 matched hospitals. NOTE Standardized differences represent differences in means in units of standard deviation between the high and low staffing group for each covariate expressed as a percentage.
a
The balancing score for the high and low staffing hospital groups is estimated through the matching process; thus, there are no values prior to matching.