3.1 Slack Resource Status
The efficiency of 23 tertiary general public hospitals in 2015–2019 is analysed by DEAP 2.1 software. Based on Mehrtak et al.’s [21] method of dividing the DEA’s overall efficiency score into 0 to 0.6, 0.6 to 0.8, and 0.8 to 1 levels, the slack resources was divided from 0 to 0.2, 0.2 to 0.4, and 0.4 to 1, corresponding to low slack, medium slack, and high slack, as shown in Figure 1.
As can be seen from Figure 1, 23 tertiary general public hospitals have slack resources. Among them, slack resources were most significant in 2018, with 13.04% of hospitals in a state of high slack and 65.22% in a state of low slack. In 2015, there were no hospitals with high slack, and 78.26% of hospitals had low slack. Overall, slack in 23 hospitals was on the rise from 2015 to 2018, with significant reduction in 2019.
3.2 Impact of Slack Resources on the Quality of Medical Care
3.2.1 Descriptive Analysis
Descriptive statistics about slack resources, quality of medical care, and related control variables are shown in Table 1. To avoid the problem of heterogeneous variance, we treated the ratio, price, or same variables with large differences with a number conversion. Referring to the ‘ln(a – 1)’ approach to observation data of 0 in Woodridge [22], we took .00001 for mortality in the low-risk group of 0 before a number conversion. Because the mortality data in the low-risk group ranged from 0 to 1, treating .00001 did not have a deviation effect on the overall results. Slack resources are valued at 0 or 1 and are not ratio variables, so we did not use number conversion. The standard deviation of each variable is below 10, indicating that the interference of outliers on the result is at a low level, so we did not have a tail-end treatment.
Table 1. Descriptive analysis of variables
Variable
|
Code
|
Calculation
|
Dependent variable
|
|
|
Mortality in the low-risk group[23]
|
lnlrgm
|
Number of deaths in the low-risk group / Number of cases in the low-risk group×100%
|
Independent variable
|
|
|
Slack resources
|
slack
|
1- DEA efficiency score
|
Control variables
|
|
|
Hospital staff or beds[24]
|
lnsta
|
The total number of staff.
|
lnbed
|
There is a real number of beds, fixed at the end of the year there are beds.
|
GDP per capita[25]
|
lngdppc
|
the gross regional product / resident population of a region achieved within one year.
|
The proportion of the elderly population[26]
|
lnaging
|
total number of persons / population over 65 years of age *100%
|
Resident population density[27]
|
lndensi
|
the number of people actually living in an area for more than half a year / the area of land in the area *100%
|
The level of urbanization[19]
|
lnurban
|
urban population / Total population (including agriculture and non-agriculture) *100%
|
Health expenditure as a percentage of general public budget expenditure[19,28]
|
lnexpen
|
government spending on health care / expenditures arranged by the financial departments at all levels for the planned allocation and use of centralized general budget revenues *100%
|
3.2.2 Correlation Analysis and Collinearity Test
In general, a correlation coefficient greater than .8 between two variables indicates a strong correlation. The Pearson correlation coefficients are shown in Table 2. In 2015–2019, there was a strong correlation between the actual number of beds and the total number of hospital employees (.942), indicating that there may be multiple collinear problems in subsequent regression models.
To test the relationship between the independent variables and dependent variables, we included the quadratic and cubic regression models. There is a high correlation between the quadratic and cubic regression models, but this did not hinder the results of the study [29].
To further test the multicollinearity problem, we carried out a variance inflation factor (VIF) test. In the VIF1 column in Table 2, the VIF value of the total number of hospital staff is 10.48. After rejecting the variable, in the VIF2 column the VIF value of each variable is less than 10, and the average VIF value is 2.90, indicating that there are no longer multiple collinearities between the variables. Therefore, we could do the next regression model analysis, which was not expected to affect the model estimates.
Table 2. Correlation analysis of variables
|
M±SD
|
lnlrgm
|
slack
|
lngdppc
|
lnaging
|
lndensi
|
lnurban
|
lnexpen
|
lnsta
|
lnbed
|
Mean VIF
|
lnlrgm
|
-4.971±3.275
|
1.000
|
|
|
|
|
|
|
|
|
|
slack
|
0.137±0.144
|
-0.13
|
1.000
|
|
|
|
|
|
|
|
|
lngdppc
|
12.070±0.619
|
-0.001
|
-0.109
|
1.000
|
|
|
|
|
|
|
|
lnaging
|
2.567±0.187
|
-0.021
|
-0.169*
|
0.732***
|
1.000
|
|
|
|
|
|
|
lndensi
|
9.118±1.134
|
-0.016
|
-0.017
|
0.775***
|
0.441***
|
1.000
|
|
|
|
|
|
lnurban
|
4.583±0.068
|
-0.025
|
0.051
|
0.513***
|
0.151
|
0.766***
|
1.000
|
|
|
|
|
lnexpen
|
1.852±0.260
|
0.169*
|
-0.147
|
0.318***
|
0.118
|
0.224**
|
0.187**
|
1.000
|
|
|
|
lnsta
|
7.767±0.530
|
0.010
|
-0.500***
|
0.536***
|
0.426***
|
0.499***
|
0.351***
|
0.163*
|
1.000
|
|
|
lnbed
|
7.016±0.440
|
0.017
|
-0.535***
|
0.469***
|
0.387***
|
0.417***
|
0.314***
|
0.106
|
0.942***
|
1.000
|
|
VIF1
|
|
-
|
1.60
|
5.36
|
2.67
|
4.97
|
2.79
|
1.22
|
10.48
|
9.88
|
4.87
|
VIF2
|
|
-
|
1.59
|
5.36
|
2.67
|
4.73
|
2.76
|
1.21
|
-
|
1.98
|
2.90
|
*p<0.05,**p<0.01,***p<0.001
3.2.3 Panel Regression Analysis
We analysed the linear, (inverted) U-type and transposed S-type relationship between slack resources and quality of medical care in public hospitals, and Panel Models 1 to 3 in turn have been built in this section. Based on the robust Hausman test results, Model 1 (p = .0579) selects the random effect panel model, and Model 2 (p = .0351) of Model 3 (p = .0451) selects the fixed-effect panel model.
Through the stray level regression of the robust standard, the model results are shown in Table 3; Models 2 and 3 are significant at the 1% level, indicating a good fit for the model.
The slack resources coefficient in Model 1 is not significant, which shows that there is no linear relationship between slack resources and low-risk mortality. The quadratic coefficient of slack resources in Model 2 is significant at the 10% level, and the coefficient is positive, which indicates that there may be a U-type relationship between slack resources and low-risk mortality. The cubic coefficient in Model 3 is not significant, which indicates that there is no transposed S-type relationship between slack resources and low-risk mortality. Therefore, there is a U-shaped relationship between slack resources and mortality in low-risk groups.
Table 3. Panel regression analysis
|
(1)
|
(2)
|
(3)
|
VARIABLES
|
lnlrgm
|
lnlrgm
|
lnlrgm
|
|
|
|
|
slack
|
-3.305
|
-13.132
|
-28.158*
|
|
(-1.44)
|
(-1.60)
|
(-2.07)
|
slack 2
|
|
28.253*
|
125.666*
|
|
|
(1.74)
|
(1.76)
|
slack 3
|
|
|
-127.919
|
|
|
|
(-1.49)
|
lngdppc
|
-0.257
|
9.771
|
10.040
|
|
(-0.17)
|
(1.55)
|
(1.50)
|
lnaging
|
-0.346
|
28.028*
|
28.018*
|
|
(-0.11)
|
(1.95)
|
(1.90)
|
lndensi
|
0.150
|
75.435**
|
77.617**
|
|
(0.29)
|
(2.78)
|
(2.72)
|
lnurban
|
-1.879
|
-367.666**
|
-384.366**
|
|
(-0.61)
|
(-2.55)
|
(-2.57)
|
lnexpen
|
1.765
|
2.073
|
2.331
|
|
(1.35)
|
(0.57)
|
(0.62)
|
lnbed
|
-0.427
|
-0.227
|
0.309
|
|
(-0.43)
|
(-0.06)
|
(0.08)
|
Constant
|
6.440
|
800.808**
|
849.989**
|
|
(0.42)
|
(2.22)
|
(2.34)
|
Observations
|
115
|
115
|
115
|
R-squared
|
0.000
|
0.136
|
0.145
|
F
|
11.06
|
7.37(***)
|
6.62(***)
|
Number of hos
|
23
|
23
|
23
|
Robust z-statistics in parentheses;*** p<0.01, ** p<0.05, * p<0.1
To further explore the relationship between slack resources and quality of medical care, according to the panel regression model just described, the regression fit between slack resources and mortality in low-risk groups is plotted with Stata 15, as shown in Figure 2. By drawing a regression fit diagram and performing number conversion, we noted that as slack resources increased from 0 to about .225, low-risk mortality increased from .014% to .003%. However, the low-risk mortality rate increased to .086% when slack resources increased to about .577.