The Empirical Model
Kuznets (1955) established a relationship between economic growth and income inequality, which is known as the Kuznets curve and is a hypothetical curve that depicts how economic growth and income inequality acts together. According to the Kuznets curve, when economies grow up and income levels rise, income inequality would rise at first, then reach to peak, and finally, diminish after certain key development stages and income levels. The focus of this research is confined to four central Asian countries namely Azerbaijan, Kazakhstan, Kyrgyzstan, and Tajikistan. To investigate the impact of fiscal and monetary policies on income distribution, we use the following multivariate regression model based on prior studies (includes Furceri et al., 2021; Siami-Namini & Hudson, 2019; Azam & Raza, 2018).
$${\text{G}\text{i}\text{n}\text{i}}_{\text{i}\text{t}}= {{\beta }}_{0}+{{\beta }}_{1}{\text{M}2}_{\text{i}\text{t}}+{{\beta }}_{2}{\text{Y}}_{\text{i}\text{t}}+{{\beta }}_{3}{\text{P}}_{\text{i}\text{t}}+{{\beta }}_{4}{\text{E}\text{R}}_{\text{i}\text{t}}+{{\beta }}_{5}{\text{R}\text{R}}_{\text{i}\text{t}}+{{\beta }}_{6}{\text{G}\text{E}}_{\text{i}\text{t}}+{{\beta }}_{7}{\text{T}\text{T}\text{R}}_{\text{i}\text{t}}+{{\beta }}_{8}{\text{R}\text{M}}_{\text{i}\text{t}}+{{\beta }}_{9}{\text{F}\text{D}}_{\text{i}\text{t}}+{{\mu }}_{\text{i}\text{t}}$$
1
Where\({\beta }_{1}\dots {\beta }_{9}\)represent the slope coefficients, and the term β0 is the intercept. \(Gini, M2, Y, P, ER, RR, GEX, TTR, RM\) and \(FD\)represents income inequality; broad money (% of GDP), real GDP per capita, Inflation rate, real effective exchange rate index, real Interest rate (%), general government final consumption spending (% of GDP), total tax revenue (% of GDP), foreign remittances inflows, and financial development index respectively. Lastly, \({\mu }_{it }\)represent the stochastic error term.
On the monetary side, Saiki and Frost, (2014) shows that income inequality is increased by expansionary monetary policy, while Coibion et al. (2017) reveals that inequality is decreased by expansionary monetary policy. Accordingly, this study hypothesizes that expansionary monetary through money supply (helps to mitigate) increases inequality. Similarly, many studies (including, Adeleye, 2020; Marasli, 2016) find that interest rate has a significant negative effect on income inequality. On the fiscal side, a research study concluded that the effect of fiscal policy by government expenditures (infrastructure expenditure) on income inequality is negative (Alamanda, 2020), and by tax revenue on income inequality is negative as well (Hayrullahoglu &Tuzun, 2020; Taghizadeh-Hesary et al., 2020).
Further, many studies noted mixed, positive, and negative, the effect of GDP per capita on income inequality (Munir & Sultan, 2017; Hayrullahoglu & Tuzun, 2020). However, an increase in per capita GDP is a positive indicator of the progress of an economy. Therefore, this study hypothesizes a negative link between GDP per capita and income inequality. Furthermore, previous literature unveiled a positive link between inflation with income inequality (Berisha et al., 2020; Law & Soon, 2020; Bulir, 2001). Consequently, this study postulate that a rise in inflation will increase income inequality significantly. Moreover, some of the empirical research favors the argument that exchange rate and income inequality have a positive relationship (for instance, Deyshappriya (2017). On the contrary, the empirical study revealed a negative link between these both which means that an increase in exchange rate decreases the income inequality. In addition, Koczan & Loyola, (2021) and Bang et al., (2016) argue that foreign remittances decrease income inequality. Similarly, Emirguc-Kunt and Levine (2010) state that financial development has also a negative effect on income inequality.
In Eq. (1), we hypothesized that expansionary monetary through money supply (helps to mitigate) increases income inequality, and fiscal policy by government expenditures reduces it, while by tax revenue increases income inequality. We also hypothesized, that the effect of GDP per capita, foreign remittances and financial development have a negative link with the income inequality, while exchange rate and inflation rate have a positive link with the income equality.
Data and its sources
This study uses annual data of four selected Central Asian countries from 1995 to 20201. The data on income inequality has been obtained from the Standardized World Income Inequality Database (SWIID, 2021). However, Broad money, GDP per capita, inflation, government expenditure, and remittances data are taken from World Development Indicators (WDI, 2022). Meanwhile, data for Real interest rates are obtained from International Monetary Fund (IMF, 2022), while the real effective exchange rate data is taken from Bruegel (Darvas, 2021). The total tax revenue data has been collected from the International Centre for Tax and Development (ICTD, 2022). Financial development data are obtained from World Bank global financial development (2021). Further, we create an index of financial development for four central Asian countries by using the principal component approach (PCA) on the major two proxies of financial development i.e., Liquid Liabilities and Private credit by deposit money.
Empirical Strategy
Construction of financial development index
There are two types of approaches used in the literature to examine the effect of financial reform on the effectiveness of any economy. To begin, the researchers used various proxies of financial sector development to evaluate the effect of various financial reforms qualities and characteristics on economic performance (see Hye, 2011; Ahmed, 2007). In their study, Hye and Islam (2013) expounds that some scholars used the principal component approach to create a financial development index for their economies using the major proxies of financial sector development. This study used the principal component approach to construct the financial development index for four (04) central Asian countries by using the principal component analysis (PCA) on the major of two proxies of financial development available in the literature: Liquid Liabilities and Private credit by deposit money. The PCA is a multivariate method for analyzing associations between for multiple dependent variables. This PCA method is commonly employed in various field of research, particularly globalization and environmental index computation (Agenor, 2004). In terms of methodology, each dataset with p variables can have up to p principal component (PC), each of which is a linear combination of the original variables, with coefficients equaling the eigenvalues of the correlation of the covariance matrix. The principal component is then categorized by Eigen-values, which are equal to the component variance, in descending order. It`s worth noting that the Eigen-vectors are all of the same length (see Table 2).
Table 2
Construction of financial development index
Number
|
Value
|
difference
|
proportion
|
Cumulative value
|
Cumulative proportion
|
1
|
1.73984
|
1.47969
|
0.8699
|
|
0.8699
|
2
|
0.260157
|
|
0.1301
|
|
1.0000
|
Eigen vectors (loading) |
Variables
|
PC1
|
|
PC2
|
ll
|
0.7071
|
|
0.7071
|
pcd
|
0.7071
|
|
-0.7071
|
Source: Author estimations
Unit root test
The non-stationary characteristic of variables is very well recognized in the extant literature, which can then be minimized by transforming them to 1st difference. Regressing a random walk series on another, according to data and Kumar (2011), would produce an incorrect result. In this regard, the Augmented Dickey-Fuller (ADF) approach, proposed by (Dickey & Fuller, 1979; 1981), is applied to detect the non-stationarity. The ADF technique is required because it leads the study`s selection of the most suitable techniques for such investigation. The inquiry of the ADF test is based on the following regression.
$${\varDelta \gamma }_{t}={\beta }_{0}+{\gamma }_{t}+{\delta \gamma }_{t-1}+{\varSigma }_{t-i}^{n}{\alpha }_{t}{\varDelta \gamma }_{t-i}+{\mu }_{t}$$
2
The test assumes that the coefficient of the level lagged variable in Eq. (2) should be zero for stationarity i.e., δ = 0, and for unit root δ = 1. Whenever the null hypothesis is failed to reject, then the series is stationary and when the null hypothesis is rejected, the series is non-stationary.
Panel unit root test
For panel data analysis, Levin et al. (2002) and Im et al. (2003) proposed a panel unit root method. According to Mercan et al. (2013), these techniques (LLC and IPS) are based on the model given below as Eq. (3).
$${\varDelta \gamma }_{it}={\beta }_{i}{\gamma }_{it-1}+{\varSigma }_{j=1}^{n}{\alpha }_{ij}{\varDelta \gamma }_{it-j}+{\chi }_{it}\sigma +{\mu }_{it}$$
3
Levin et al. and Im et al. test have the null hypothesis that “for all cross-section unit βi = 0 (nonstationary)” against the alternative of “for relatively one unit βi < 0 (stationary)”.
If the considered variables are detected as a mixture of \(I\left(0\right)\) and\(I\left(1\right)\), then the panel Autoregressive Distributed Lag (ARDL) approach is applicable, and if all variables are stationary at 1st difference i.e. \(I\left(1\right)\) then we can also apply panel ARDL model.
ARDL model
To assess the robustness of the estimations, the pooled mean group (PMG) estimator introduced by Pesaran & Shin (1999) and Pesaran et al. (1999; 2001) is employed. As per Pesaran et al., (2001) the ARDL method proposed in Pesaran and Shin (1999) is valid regardless of whether variables are purely I(0), I(1), or mutually cointegrated. According to (Pesaran et al., 2001), the ARDL approach has numerous advantages over other co-integration approaches: (i) it is efficient in performing short- and long-term association among various variables that do not have the same integration order. Assuming that such variables are stationary in I(0) and I(1). (ii) ARDL approach can eliminate issues like as omitted variables and auto-correlation. (iii) This approach can be advantageous in situations with a limited sample size. The ARDL approach, notably the Pooled Mean Group estimator, gives accurate coefficients despite the possibility of endogeneity in response lag regressors. According to Pesaran et al., (1999), the ARDL model`s unrestricted error correction for the response variable (GINI) can be expressed as follows.
$${\text{G}\text{I}\text{N}\text{I}}_{\text{i}, \text{t}}={{\Sigma }}_{\text{j}=1}^{\text{p}}{{\delta }}_{\text{i}\text{j}} {\text{G}\text{I}\text{N}\text{I}}_{\text{i}, \text{t}-\text{j}}+{{\Sigma }}_{\text{j}=0}^{\text{q}}{\text{Ϭ}}_{\text{i}\text{j}}{\text{X}}_{\text{i}, \text{t}-\text{j}}+{{\mu }}_{\text{i}}+{\text{є}}_{\text{i}\text{t}}$$
4
The subscript i and t in Eq. (4) denote the country (group) and time, accordingly. As a result, the time period t = 1,…T (1995–2020) and countries i = 1,… N (in this situation, N = 4). GINI is income inequality as a dependent variable; X (Kₓ 1) is the independent variables such as broad money (M2), GDP per capita, inflation, real effective exchange rate, real interest rate, Government expenditure, total tax revenue, remittances, and financial development for country i; ui represents fixed effects. δij indicates the coefficient of lagged dependent variable; Ϭij is (K ₓ 1) coefficient of lagged explanatory variables, and є denotes error term. T must be large enough so that each country may be calculated individually.
The reparametrized form of the Equation shown below can be used to accomplish the study`s set of goals, which are dependent on the nature of the data.
$${\varDelta GINI}_{it}={\partial GINI}_{i, t-1}+{\beta }_{i}{Y}_{it}+{\varSigma }_{j=1}^{p-1}{\delta }_{i,j}{\varDelta GINI}_{i, t-j}+{\varSigma }_{j=0}^{q-1}{\phi }_{ij}{\varDelta Y}_{i, t-j}+{u}_{i}+{є}_{i, t}$$
5
Where,\({\partial }_{i}=-⟮1-{\varSigma }_{j=1}^{p}{\delta }_{i,j}⟯\),\({\beta }_{i}+ ={\varSigma }_{j=0}^{q}{\phi }_{i,j}\)
\({\delta }_{it}= -{\varSigma }_{m=j+1}^{p}{\delta }_{im}\) j = 1,2,…..., p-1. (6)
and
\({\phi }_{it}= -{\varSigma }_{m=j+1}^{p}{\phi }_{im}\) j = 1,2…. q -1.
\(\partial\) in Eq. (5) is the coefficient of the speed of adjustment towards the long-run equilibrium.
[1] Data availability statement: Data used in this study for empirical examination have been obtained from the World Development Indicators (2021), the World Bank database, Standardized World Income Inequality (2021), Darvas (2021) “Timely measurement of real effective exchange rates’, Working Paper 15/2021, Bruegel”, and International Centre for Tax and Development (ICTD) (2022).