Page 29 - Azerbaijan State University of Economics

THE JOURNAL OF ECONOMIC SCIENCES: THEORY AND PRACTICE, V.79, # 2, 2022, pp. 19-36

In order to study in detail, the extremum values of the interest burden that affect tax
revenues, we can determine the extremum points in a given range by evaluating the
third order polynomial model or cubic regression model (Table 3).

1600
2,50% 1400
2,00% 1200
1000
1,50% 800
1,00% 600
400
0,50%
200
0,00% 0
2019-01-31 2019-03-31 2019-05-31 2019-07-31 2019-09-30 2019-11-30 2020-01-31 2020-03-31 2020-05-31 2020-07-31 2020-09-30 2020-11-30 2021-01-31 2021-03-31 2021-05-31 2021-07-31 2021-09-30 2021-11-30

Interest Burden Tax revenues

Figure 4. Description of the actual graph of tax revenues by periods of change in
the interest burden (compiled by the author).

The dummy variable used in the polynomial model considers the COVID-19
lockdown effect in the model.

Table 3. Polynomial Regression Assessment of the Relationship between Tax
Revenues and the Interest Burden (for the case of Azerbaijan)

Variables Dependent
variable: Tax_Rev

c -14437.85
(-2.344531)
2560364.

(2.635003)

-1.38E+08

(-2.763731)

2.43E+09

(2.877102)
∗ 302714.2

(1.657458)

∗ -35347045

(-1.802849)

∗ 1.02E+09

(1.953688)
AR(6) 0.693504
4.260883

29