This paper uses a concentration index to measure the health inequality among migrant workers. Based on the above treatment of health and income rank variable, according to the method of Donnell et al (2008)[32],the health concentration index (CI) is expressed as:
Firstly, to calculate the RIF value of the concentration index.
$${\nu }^{CI}\left({F}_{h,R}\right)=E\left[RIF\left(h,R;{\nu }^{CI}\right)\right]={E}_{x}\left\{E\left[RIF\left(h,R;{\nu }^{CI}\right)|X=x\right]\right\}={E}_{x}\left({\beta }^{T}X+\epsilon \right)={\beta }^{T}X$$
7
Empirical Results
The Health Inequality on Self-employment of Migrant Workers and Decomposition
To examine the impact of self-employment on health inequality of migrant workers, we use the RIF-I-OLS decomposition method to estimate the RIF value of the concentration index and analyze the health inequality results from subtle changes from the health distribution, which is able to examine the impact of changes in explanatory variables on health inequality. Table 2 presents the decomposition on health inequality by RIF-I-OLS method, model a to model d shows the decomposition results by adding control variables in turn. The result shows that self-employment has a significantly negative effect on the health inequality of migrant workers, indicating that when migrant workers more likely to choose self-employment, the degree of health inequality will decrease. However, the results in Table2 show that the coefficient of self-employment is still small, indicating that although self-employment has a statistically significant effect on health inequality of migrant workers, probably because health inequality of migrant workers do exist objectively, thus the change of self-employment can hardly make a significant effect this objective fact.
We also pay attention to the other variables. From the perspective of individual characteristics, men have lower health inequality compared to women, indicating that there is a gender health gap and female migrant workers are more vulnerable to health risks. The health inequality of migrant workers increases significantly with increasing age, higher education of migrant workers have lower health inequality, but communist variable has no significant effect on the health inequality of migrant workers. From the perspective of family characteristics, the health inequality of married migrant workers is relatively lower, the degree of health inequality of migrant workers is higher when a family has more children, and the larger family size and higher household income will decrease the degree of health inequality. From the perspective of job characteristics, inter-provincial mobility significantly reduces health inequalities, but with the time of migration increasing, migrant workers face higher health inequality. The health inequality is worse when migrant workers has longer work time, And medical insurance has significantly decreased the health inequality of migrant workers. From the perspective of regional characteristics, the degree of health inequality is lower when migrant workers living in eastern, but the degree of health inequality is higher when migrant workers living in western and northeastern region.
Table 2 Impact of self-employment on health inequality of migrant workers:
RIF-I-OLS decomposition method
Variable
|
a
|
b
|
c
|
d
|
Self-Employment
|
-0.0022***
(0.0005)
|
-0.0018***
(0.0005)
|
-0.0012**
(0.0006)
|
-0.0016***
(0.0006)
|
Gender
|
-0.0021***
(0.0005)
|
-0.0020***
(0.0005)
|
-0.0019***
(0.0005)
|
-0.0019***
(0.0005)
|
Age
|
0.0295***
(0.0014)
|
0.0258***
(0.0015)
|
0.0229***
(0.0016)
|
0.0226***
(0.0016)
|
Education
|
-0.0062***
(0.0010)
|
-0.0029***
(0.0010)
|
-0.0041***
(0.0010)
|
-0.0039***
(0.0010)
|
Political status
|
0.0003
(0.0014)
|
0.0006
(0.0014)
|
0.0006
(0.0014)
|
0.0005
(0.0014)
|
Marriage
|
|
-0.0060***
(0.0014)
|
-0.0061***
(0.0014)
|
-0.0060***
(0.0014)
|
Number of children
|
|
0.0137***
(0.0035)
|
0.0150***
(0.0035)
|
0.0168***
(0.0035)
|
Family size
|
|
-0.0246***
(0.0034)
|
-0.0249***
(0.0034)
|
-0.0235***
(0.0034)
|
Per Capita Income
|
|
-0.0716***
(0.0057)
|
-0.0675***
(0.0057)
|
-0.0589***
(0.0059)
|
Inter-Provincial Mobility
|
|
|
-0.0022***
(0.0005)
|
-0.0015***
(0.0006)
|
Length of Mobility
|
|
|
0.0165***
(0.0026)
|
0.0163***
(0.0026)
|
Work Hours
|
|
|
-0.0091***
(0.0017)
|
-0.0087***
(0.0017)
|
Medical Insurance
|
|
|
-0.0051***
(0.0012)
|
-0.0051***
(0.0012)
|
Eastern
|
|
|
|
-0.0013*
(0.0008)
|
Western
|
|
|
|
0.0027***
(0.0008)
|
Northeastern
|
|
|
|
0.0033**
(0.0013)
|
Constant
|
-0.0024**
(0.0010)
|
0.0537***
(0.0042)
|
0.0612***
(0.0044)
|
0.0542***
(0.0046)
|
R-squared
|
0.0081
|
0.0106
|
0.0118
|
0.0123
|
Sample Size
|
86348
|
Note : ***, **, * are statistically significant at 1%,5%,10%, robust standard error in parentheses.
Robustness Test
We conduct robustness test from the following three aspects: 1.Eliminating the impact of urban differences. Floating population usually migrates to big cities, in China, cities can be divided by city size and economic development conditions, according to this, and we eliminate megacities like Beijing, Shanghai, Guangzhou and Shenzhen. In table 3, model (1) shows that after excluding four megacities, migrant workers’ choice of self-employment can still significantly reduce the degree of health inequality. 2. Excluding outliers: 5% truncated tails before and after the income variable. Outliers may lead to unture results and the regression curve may deviate from the true trend, thus affecting the true relationship between the variables. Since health inequality is income-related inequality, this paper makes a truncation of the income rank variables of migrant workers by 5% before and after, the results of model (2) in Table 3 show that the effect of self-employment on health inequality is still significantly negative. 3. Segmentation explanatory variables. In this paper, the explanatory variables are divided into subsistence self-employment and opportunity self-employment according to the employment status of migrant workers. Opportunity self-employment is defined as hiring at least one worker, corresponding to “employers”, subsistence self-employment is defined as not hiring others, corresponding to “self-employed workers”. The results in Table 3 show that both opportunity self-employment and subsistence self-employment have a significant negative effect on health inequality, the results show that the research conclusions are robust.
Table3 Robustness Test
Variable
|
(1)
|
(2)
|
(3)
|
(4)
|
Self-Employment
|
-0.0017***
|
-0.0026***
|
|
|
|
(0.0006)
|
(0.0006)
|
|
|
Opportunity Self-Employment
|
|
|
-0.0020**
|
|
|
|
|
(0.0010)
|
|
Subsistence Self-Employment
|
|
|
|
-0.0010*
|
|
|
|
|
(0.0006)
|
Other Variables
|
|
|
control
|
control
|
Constant
|
0.0578***
|
0.0334***
|
0.0539***
|
0.0554***
|
|
0.0049
|
0.0051
|
(0.0046)
|
(0.0045)
|
R-squared
|
0.0132
|
0.0070
|
0.0122
|
0.0122
|
Sample Size
|
77,463
|
80801
|
86438
|
86438
|
Note : ***, **, * are statistically significant at 1%,5%,10%, robust standard error in parentheses.
Heterogeneity
Individuals with different characteristics will have different levels of health, so this paper conducts a sub-sample test on the migrant workers based on the differences in education, income and social integration. According to the education of migrant workers, migrant workers are divided into three levels: (1)primary school and below, (2)junior high school, (3)senior high school and above. According to the income of migrant workers, reflected in the questionnaire as: “How much was your personal income last month ?”The data shows that the sample average income of migrant workers last month is RMB 4796.85. Based on this, this paper divides the samples of migrant workers into two groups, the samples with income higher than RMB4796.85 are recorded as (1)high income migrant workers, the samples with income lower than RMB4796.85 are recorded as (2)low income migrant workers. According to the social integration of migrant workers, this paper uses the residence willingness of migrant workers to stay in inflow area as proxy variable, which is reflected in the questionnaire as “If you intend to stay in this city, how long do you expect to stay?”We put the answer “I don’t want to stay here” and “I have no idea” is assigned to 0, “I plan to stay here but I don’t know how long”=1, “I will stay here for 0-4years”=2, “I will stay here for 5-9years”=3, “I will stay here for more than 10years”=4, “I plan to settle here”=5. According to this, we have generated a social integration variable, and residence willingness of migrant workers more than 5 years is recorded as (1) high social integration, residence willingness of migrant workers less than 5 years is recorded as (2) low social integration.
Model a in Table 4is a sub-sample test by education. The RIF-I-OLS decomposition results show that self-employment can significantly reduce the health inequality of migrant workers for primary schools and below migrant workers, but it is not significant for the other three subsamples. Model b in Table 4 is a sub-sample test by income. The results show that self-employment can significantly reduce the health inequality of migrant workers for low-income migrant workers, but the effect for high-income migrant workers is positive and it is not significant, indicating that the increase of the probability of migrant workers choosing self-employment can significantly reduce the degree of health inequality for low-income migrant workers. Model c in Table 4is a sub-sample test by social inclusion. The RIF-I-OLS decomposition results show that self-employment has a significantly negative effect on health inequality for the low social inclusion migrant workers, but has no significant effect on migrant workers with high social integration. The above results show that self-employment can alleviate the health inequality of migrant workers, and particularly significant in migrant workers with low-education, low-income and low social inclusion.
Table 4 Heterogeneity
Variable
|
a. by education
|
b. by income
|
c. by social inclusion
|
|
(1)
|
(2)
|
(3)
|
(1)
|
(2)
|
(1)
|
(2)
|
Self-Employment
|
-0.0043**
|
0.0002
|
-0.0014
|
0.0006
|
-0.0017**
|
-0.0012
|
-0.0024***
|
(0.0017)
|
(0.0007)
|
(0.0008)
|
(0.0007)
|
(0.0008)
|
(0.0008)
|
(0.0008)
|
Other Variable
|
Control
|
Control
|
Control
|
Control
|
Control
|
Control
|
Control
|
Constant
|
0.0427***
|
0.0540***
|
0.0216***
|
0.0029
|
0.0645***
|
-0.0012
|
0.0492***
|
|
(0.0126)
|
(0.0063)
|
(0.0068)
|
(0.0064)
|
(0.0067)
|
(0.0008)
|
(0.0064)
|
R-squared
|
0.0086
|
0.0064
|
0.0078
|
0.0006
|
0.0105
|
0.0162
|
0.0100
|
Sample Size
|
15983
|
42754
|
27701
|
33963
|
52475
|
41907
|
44531
|
Note: ***, **, * are statistically significant at 1%,5%,10%, robust standard error in parentheses.
Further Discussion
The effect of self-employment on self-rated health of migrant workers
This part discusses the impact of self-employment on the self-rated health of migrant workers. Table5 shows the effect of self-employment on health of migrant workers using the ordered probit model. Models (1) to (4) show the regression results of adding control variables in turn. The results show that after adding the control variables of individual characteristics, family characteristics, job characteristics and regional characteristics gradually, self-employment has a significant positive effect on health of migrant workers, indicating that when migrant workers incline to choose self-employment, their physical health will also improve. Self-employment can significantly promote the health of migrant workers.
Unlike the other developing countries in the world, migrant workers in China are more likely to engage in wage employment based on an employment relationship, accumulate wealth and acquire capital, then turn to self-employment. Migrant workers engage in heavy physical hired work is more common, while self-employment may lead to higher income and a freer working environment [33]. Grossman’s demand of health theory believes that investment in health is an important way to maintain health[1], and thus compared with traditional employment with poor environment and high labor intensity, migrant workers’ choice of self-employment can reduce the health depletion from work, and have a positive impact on health.
Table 5 The Effect of Self-employment on Migrant Workers’ Health
Variable
|
(1)
|
(2)
|
(3)
|
(4)
|
Self-employment
|
0.0509***
(0.0115)
|
0.0468***
(0.0116)
|
0.0849***
(0.0125)
|
0.0988***
(0.0128)
|
Individual Characteristics
|
control
|
control
|
control
|
control
|
Family Characteristics
|
--
|
control
|
control
|
control
|
Job Characteristics
|
--
|
-
|
control
|
control
|
Regional Characteristics
|
--
|
--
|
--
|
control
|
Pseudo R2
|
0.0425
|
0.0466
|
0.0497
|
0.0510
|
Sample Size
|
86438
|
Note: ***, **, * are statistically significant at 1%,5%,10%, robust standard error in parentheses.
Mechanism Analysis of Self-employment Affecting Health Inequality of Migrant Workers
The empirical results above show that the increase of the probability on migrant workers choosing self-employment can reduce the degree of health inequality, this part attempts to discuss the mechanism of this effect. We choose the accessibility of public welfare obtained by migrant workers as a mediator variable, and divides it into two pathways: acceptance of health education and the establishment of health records. As a group of dominated by physical labor, migrant workers are vulnerable to diseases, while they are not well-educated, so it is necessary for their communities and work units to provide them with health education, such as the prevention of occupational disease, infectious disease and chronic disease, the reproductive health, maternal and child health, mental health, self-help of public emergencies, and other aspects of health education. At the same time, the establishment of health records is a new product under the development of Internet technology in recent years. Health records are not only a tool for recording illnesses and treatment processes, but also an integration of information centered on residents ' health. The establishment of health records is an important guarantee for the community to carry out various health care works and meet the needs of the floating population for health services, such as prevention, medical and health, rehabilitation, health education, fertility guidance. It is also a basic measure to improve the accessibility of basic public services in health and family planning for the floating population.
Table 6 shows the results of mediating effect test using the health education variable as a mediator variable, the results reflect that the increasing probability of migrant workers choosing self-employment can improve the probability of receiving health education, and health education of migrant workers can make them acquire more health knowledge, so that they can have better protection for themselves in the workplace, which is conducive to promoting individual health and reducing the occurrence of health inequality. At the same time, self-employment also promotes the use and understanding of health records for migrant workers, and the establishment of health records can observe the changes of individual health and analyze the trend of disease development and treatment effect, which is conducive to health care decision-making and maintenance of individual health. As a basic safeguard measure for the demand of prevention and medical care, health records can meet the basic needs of residents, and have a more significant health promotion for the migrant workers with lower income, thus reducing health inequalities.
As the main source of labor in the Entity Industry, the migrant workers have made great contributions to Chinese industrialization and urbanization. But most migrant workers in cities are engaged in high-intensity work, which seriously damages their health. In recent years, with the gradual relaxation of some restriction policy on the floating population in cities, the health status of migrant workers has been paid attention to and gradually improved, but at the same time, the health gap in migrant workers has begun to appear, different employment status and employment relationship are some of the reasons of health inequality in migrant workers. Therefore, it is necessary to take measures to protect the health of migrant workers and to promote health equality among them. And it is an important way for promoting a fairer health field of migrant workers to improve the accessibility of migrant workers' public health welfare. Health and health inequality are not only derived from genetic and hereditary factors, but also from the physical environment and behavior habits of individuals, as well as the imbalance between supply and demand of public health services. Therefore, health inequality can be intervened by risk management and equalization of public welfare. By providing health education and establishing health records for the migrant workers, it can not only provide health knowledge for migrant workers, improve their incorrect lifestyles and reduce the incidence of diseases, it can also intervene, assess and manage the health and diseases of migrant workers, identify potential health risks and respond to health needs through scientific and technological way, which will improve the health status of migrant workers and alleviate the health inequality of them.
Table 6 Mechanism Analysis of Self-employment Affecting Health Inequality
Variable
|
Mediator Variable
|
Dependent Variable:
Health Inequality
|
Health Education
|
Health Record
|
Self-Employment
|
0.0865***
|
0.04073***
|
-0.00155***
|
-0.00167***
|
(0.0112)
|
(0.00331)
|
(0.000571)
|
(0.00060)
|
Health Education
|
|
|
-0.00365***
|
|
|
|
(0.000674)
|
|
Health Record
|
|
|
|
-0.00253***
|
|
|
|
(0.00064)
|
Other Variables
|
control
|
control
|
control
|
control
|
Constant
|
1.217***
|
0.61086***
|
0.0575***
|
0.06033***
|
(0.0928)
|
(0.02733)
|
(0.00458)
|
(0.00488)
|
R-squared
|
0.0333
|
0.0377
|
0.0126
|
0.0133
|
Sample Size
|
86438
|
Note: ***, **, * are statistically significant at 1%,5%,10%, robust standard error in parentheses.