The dynamics of economic growth and income inequality in Romania: a statistical analysis of economic transformation in post-eu accession (2006-2021)

Research Hypothesis

The central hypothesis of this study is that economic growth, as represented by Romania's Gross Domestic Product (GDP), significantly impacts income inequality, measured using the GINI index. Specifically:

Null Hypothesis (H₀): There is no statistically significant relationship between GDP and the GINI index in Romania from 2006 to 2021. This implies that changes in GDP do not influence income inequality.
Alternative Hypothesis (H₁): There is a statistically significant negative relationship between GDP and the GINI index in Romania from 2006 to 2021. This suggests that as GDP increases, income inequality decreases.

Data Description and Collection

The study relies on secondary data sourced from the World Bank Open Database. Two primary variables were used:

Gross Domestic Product (GDP):
Representing Romania's economic output, GDP was measured in constant USD to account for inflation. It reflects the total value of goods and services produced within the country each year.
This variable serves as the independent variable, influencing income inequality.

GINI Index:
The GINI index quantifies income inequality on a scale of 0 to 100, where 0 represents perfect equality and 100 represents maximum inequality.
This variable acts as the dependent variable, influenced by changes in GDP.

The dataset spans 2006 to 2021, providing a comprehensive view of Romania’s economic and social landscape during its post-European Union (EU) accession period.
Methodology
Linear Regression Analysis

To test the relationship between GDP and the GINI index, a simple linear regression model was constructed.

Diagnostic Checks

Several diagnostic tests were conducted to validate the regression model:

Residual Analysis: Checked for normality using the Shapiro-Wilk test.
Homoscedasticity: Assessed using the Breusch-Pagan test to verify constant variance in residuals.
Autocorrelation: Evaluated using the Durbin-Watson test to detect correlations in residuals over time.

Findings
Model Results

Correlation Coefficient (R): 0.739

F-Statistic: 16.850 (p = 0.001)
Indicates that the overall model is statistically significant at a 1% level, reinforcing the relationship between GDP and the GINI index.

GDP Coefficient (Unstandardized): -2.472E-11

P-Value for GDP Coefficient: 0.001
Demonstrates that the relationship between GDP and the GINI index is statistically significant.

Diagnostic Test Results

Homoscedasticity: The Breusch-Pagan test identified evidence of heteroscedasticity (p = 0.033), indicating non-constant variance in residuals.
Autocorrelation: The Durbin-Watson statistic (1.126) revealed some positive autocorrelation in residuals, suggesting temporal patterns in unexplained factors.