developed in depth, and that the government's timely
and appropriate intervention is particularly needed to
help traditional and new rural financial institutions
embark on the development path of inclusive finance.
The view point of Jianbing (2018) is that Fintech has
become a new vitality in rural economic development
from budding to vigorous development in just a few
years. Wenqi (2018) combed and summarized the
theory of rural finance, summarized and analyzed the
development process and current situation of rural
finance, constructed a panel model to study the
mechanism of rural financial development and
farmers’ income growth. Yongcang (2021) deeply
analyzed the evolution process and structural changes
of rural household income growth, the characteristic
facts and evolution trends of digital finance, and
constructed a theoretical framework for the influence
of digital finance on household income growth.
3 SVAR MODEL
The Vector Auto Regressive Model to study the
interaction between two or more variables is referred
to as VAR model. The VAR model is essentially a
multivariate data analysis method, which takes each
endogenous variable in the system as a function of the
lag value of all endogenous variables in the system.
Therefore, this model successfully extended the
univariate autoregressive model to the vector
autoregressive model composed of multiple time
series variables. If the VAR model is not based on
strict economic theory, the explanatory variables are
all lagged terms, and no parameter constraints are
imposed, then it can avoid identification problems
and endogenous explanatory variable problems, so it
is structural and non-restrictive, and is recorded as
SVAR. The important premise of the realization of
the VAR model is that the time series corresponding
to all variables are stable. Therefore, this paper uses
the ADF unit root test method to test the stationarity
of the selected time series and their difference terms.
Its basic form is as follows:
∆Y
=β
+γt+∅Y
+
∑
β
∆Y
+δ
(1)
Where, ∅=0, the original series is a non-
stationary series, and ∅<0, the original series is a
stationary series. The general mathematical formula
of the SVAR model is shown as follows, setting the
number of variables as N and the lag order as p, where
c is the n-dimensional constant column term, 𝜀
is
the n-dimensional error column vector, the
coefficient α is a matrix of N×N:
Y
=c+
α
Y
+
α
Y
+
α
Y
+⋯+
α
Y
+
ε
(2)
Where, Y
=(y
,
,y
,
,y
,
,⋯,y
,
) , c=
(c
,c
,c
,⋯,c
),
ε
~ΠN(0,Ω)
,
ε
=(ε
,
,ε
,
,ε
,
,⋯,ε
,
)
.
Π
=
π
,
⋯
π
,
⋮⋱⋮
π
,
…
π
,
, j=1,2,3,⋯,p
(3)
If the model meets the conditions: (1) The n*n-
dimensional matrix formed by the coefficient is not 0
and p>0; (2) The roots of the characteristic
equation fall outside the unit circle; (3) ε
are
independent of each other. At this time, ε
is an n-
dimensional white noise vector sequence, also called
an impact vector. Cov(ε
x
)=E(ε
x
)=0, (
j=1,2,3,⋯), that is, the lag period of x
, x
and ε
is not correlated.
In order to solve the problem of correlation
between the random error terms corresponding to
different equations, we usually use Cholesky
decomposition to attribute the relevant part to the
random disturbance term of the first variable in the
SVAR system. Processing in this way can make the
random error terms corresponding to different
equations irrelevant.
The SVAR model estimation method used in this
paper is OLS estimation, and the model parameter
matrix is:
A
=
a
,
⋯a
,
⋮⋱⋮
a
,
…a
,
,i=1,2,3,⋯,p (4)
Then find the OLS estimate of the model
parameter matrix A
,A
,⋯,A
, that is, find the
(A
,
A
,
⋯,A
) that makes the following formula
obtain the minimum value:
Q=
∑
y
−
∑
A
y
y
−
∑
A
y
(5)
For the order determination, this article uses the
AIC and SC information criteria, also called the
minimum information criterion, to determine the lag
order of the SVAR model:
AIC=−2l/T+2n/T,SC=−2l/T+nlnT/T
(6)
Where, l=−
(1 + ln2π) −
lnΣ
, n is the
number of parameters that the model needs
to estimate,
n=pN
. The minimum information criterion is to
take p=1,2,3... for AIC or SC respectively. When AIC
or SC=min, the corresponding p is the appropriate
order of the model, and the corresponding
A
1
,
A
2
,
⋯,A
P
is the best model parameter estimation.
After establishing the SVAR model, we need to
make a judgment on the stability of the SVAR model,
based on the value of the characteristic root. Calculate
the value of the characteristic root and compare the
absolute value of its reciprocal with 1. If the absolute