After binary logistic regression analysis and structural equation model mediation effect analysis, it was concluded that BMIUE, personal social security card application and social integration not only directly promote the settlement intentions of the floating population but also promote the settlement of the floating population in their current residence through the intermediary variable of social integration.
BMIUE, social security cards, and settlement intentions
Participating in BMIUE in the current residence is very important for the future settlement intentions of the floating population. Participation in BMIUE has a positive impact on the settlement intentions of the floating population, and the impact on the settlement intention is greater than that of participating in other types of insurance(47), which is consistent with the findings of previous studies (48, 49). In addition, researchers previously found that the participation of the floating population in BMIUE in big cities would contribute to their intentions to settle down(50). More importantly, participating in BMIUE can improve the risk resistance of the floating population at their current residence, reduce their cost of living and reduce their economic burden to a certain extent(51-53). BMIUE is paid for by both the employer and the employee(54), and the employer pays more than each individual. Employees only need to pay for a certain number of years to enjoy higher rates of medical insurance reimbursement for life. Therefore, this will enhance the floating population's intention to settle down to some extent. Even without considering the preferences of migrant workers, the participation in social insurance still has a positive impact on the willingness of the floating population to settle down(55-57).
Social security cards had a positive effect on the settlement intentions of the floating population, which is consistent with previous studies(58, 59). It has been documented that the issuance of and application for a social security card is an important push to relieve the worries of the floating population and promote the construction of new urban areas. The social security card is an important guarantee for the floating population that encourages them to integrate into their current residence and live a stable life(60). Migrants can receive a social security card as long as they are insured in their place of residence. These cards are used for the identification of their medical insurance, and they are also used to record the basic information of the insured persons, payment status, treatments, payment of medical funds and other information(61). Therefore, even though it had an effect on the settlement intention in the single-factor analysis and no effect on the regression analysis, this study still included the social security card in the final model.
Social integration and settlement intention
Social integration has become an important factor affecting the settlement intentions of the floating population(62). With the development of urbanization, the floating population has paid increasing attention to their acceptance in the local society (50). The "people-centered" urbanization policy put forward by the Chinese government in 2014 shows that urbanization is the urbanization of people, and the degree of social integration is closely related to the degree of the acceptance of the floating population by the local people(63-65). This is consistent with the selection of the social integration measurement criteria in this paper because the current residence provides abundant social resources and conditions for the floating population, which will help them integrate into the local life as soon as possible(66). The longer the influx takes, the stronger the positive effect of social integration on settlement intentions(67).
The mediating effect of social integration
Participation in BMIUE in the place of residence is an important indicator to measure social integration(68). Participation in BMIUE will promote the social integration of the floating population in the local area(69), which is consistent with the results of this study. This may be because the eligibility for BMIUE indicates that the floating population has a fixed source of income and a stable work unit in their current place of residence, and their living conditions are relatively good, which can meet the basic living needs of the floating population. Participating in social health insurance is the only requirement for obtaining a social security card. Therefore, BMIUE and social security cards, which are closely related to social security, are important factors affecting the social integration of the floating population. They will increase the sense of belonging of the floating population in their current place of residence and ultimately improve their willingness to settle down(70).
Settlement intention and public health
An increase in permanent residence will not only improve the health management level of the floating population in their place of residence but also promote the improvement of public health. The residents' health records are an important part of the twelve contents of the national basic public health service, which takes personal health as the core and satisfies the residents' self-care and health management (71). Studies have shown that long-term settlement intention can significantly promote the service utilization of the health records of the floating population(72), which is beneficial to the physical health of the floating population. At the same time, settlement intention will also improve the level of public services(73-75). As their willingness to stay increases, so does the prevention of communicable and noncommunicable diseases in the place of residence. This is because the willingness to stay promotes urbanization, which leads to an increase in global risk factors for infectious and noncommunicable diseases(76-78). Specifically, China's public health service system for the floating population is not sound, and there is a lack of disease data from the floating population on infectious diseases and chronic noncommunicable diseases, making it difficult to establish a disease surveillance system (78-80). This leads to the absence of prevention and the control of disease in vulnerable groups such as the floating population in China, and makes infectious diseases such as tuberculosis an important threat to public health(78, 79). For example, in the COVID-19 epidemic in 2019, the floating population will be at increased risk of COVID-19 infection due to their high rates of chronic disease comorbidities (81-83). Additionally, because of their different medical insurance coverage, some vulnerable groups will not be able to timely treatment(78, 82). As a result, some countries, including China, have taken measures to control migration flows to control the COVID-19 epidemic(22).
To sum up, BMIUE and social security cards, as part of social security, have a direct positive impact on the floating population. Social integration, which is closely related to social security and public services, also has a direct positive impact on the resettlement intentions of the floating population. This study proved the mediating effect of social integration through constructing a model; BMIUE and social security cards can promote the settlement intentions of the floating population through social integration. The increase in permanent residence will eventually improve the health management level of the floating population and promote the development of public health.
However, this study also has some limitations. The results of this study are based on mining of existing data. Due to the limited variables in the original data, the reliability of some indicators and the intermediary ratio is low. If one can add new effective variables in the future, the explanation of the influence of medical insurance and social security cards on the settlement intentions of the floating population will be more complete.