## 2 Related Work
### Coupling and Coordination Studies  
The coupling and coordination between a variety of correlated subsystems are seen in the field of finance and economic. These studies have considered the coupling and coordination between environmental pollution and economic development [12], human capital and economic growth [13; 14], tourism industry and regional economic development [15], resource endowment, ecological environment, and economic development [16], digital economy and green finance [17], intellectual property and economy [18], urbanization and ecological environment [19]. It is also interesting to note that in [20], the coupling and coordination calculation is used to determine predictors that indicate obstacles in economic development by comparing the coupling and coordination between different predictors (a total of 10 subsystems are considered based on first-level predictors). Several studies focused on proposing coupling mechanisms between technological innovation and financial development. In [21], the important of the coupling and coordination between technological innovation and financial development is recognized and advocated appropriate policies to facilitate the coupling and coordination. In [22], three levels of mechanisms are proposed to enhance the coupling and coordination of technological innovation and financial development: (1) financing of science and technology industrial parks; (2) setting up technology financial institutions; and (3) subsidizing market-oriented operation. In [23], the coupling mechanisms proposed include the setup of independent regulatory Institutions, encourage the integration of research and development in enterprises, provide support for big data and wide-band connectivity, and enact suitable governmental policies. In [24], a dynamic model to facilitate the coupling and coordination of the two subsystems is proposed. The model consists four feedback loops with similar steps: financial investment on research institutions, which would produce more papers and patents, then in turns, the intellectual properties could lead to new products and the growth of the local economy. The improved economy would generate more taxes, which makes it possible for the local government to invest more. Several studies [2; 3; 4; 5; 6; 7; 8; 9] adopted the same set of models and formula for calculating the degree of coupling and coordination between technological innovation and financial development. Some studies [25] described the formula used to calculate the comprehensive evaluation index, the coupling degree, and the coupling and coordination degree with citations but did not explicitly provide the formulas. From the context, it appears that the formulas are likely the same. In [2], a total of six predictors for both the technological innovation and financial development are used to model the coupling between new industry and traditional industry, instead of treating technological innovation and financial development as two subsystems. In [3], the focus is on applying the set of formulas to discover the economical development in China based on the 2002-2012 data, while in [4], the focus is on examining the impact on economic efficiency without presenting the detailed outcomes of the degree of coupling and coordination. In [3], two categories of seven predictors are used to model the technological innovation subsystem, and three categories of seven predictors are used to model the financial development subsystem. The proposed model is applied to data collected in China between 2002 and 2012. In [5], two categories of four predictors are used for the technological innovation subsystem, and three categories of three predictors (one per category) are used for the financial development subsystem. The model is applied to the 2008-2013 data. In [26], four predictors for the technological innovation subsystem are introduced (no category is created), and three predictors for the financial development subsystem (no category is created). The way the coupling degree \(C\) is calculated is non-mainstream.