| Data Sources | | | |
| Environmental Footprint (EF) Data | Global Footprint Network (2018) | | Serves as the dependent variable capturing the ecological pressure from economic activities; replaces traditional pollution indicators. |
| Tourism & Travel (T&T) as % of GDP | World Data Atlas; China Statistical Yearbook; China Bureau of Statistics | | Measures the tourism sector’s contribution to economic activity and its environmental implications; used to test tourism-led EKC by including T&T2. |
| GDP (Economic Development Indicator) | World Development Indicators (WDI) | | Core variable for testing the EKC hypothesis and modeling the scale effect of economic growth. |
| Energy Use (EU) | World Development Indicators (WDI) | | Captures the pollution intensity of energy consumption, aligned with the IPAT framework. |
| Joint Venture (JV) / FDI Proxy | Ministry of Commerce of China, Chinese Investment & JV Records | | Used as a proxy for FDI to test the Pollution Haven and Pollution Halo hypotheses within China. |
| Open Trade (OT) | World Development Indicators (WDI) | | Represents trade openness to evaluate scale, composition, and technique effects on EF. |
| Constructed Variables | | | |
| Tourism Non-linear Term (T&T²) | Computed squared term of T&T as % of GDP | | Allows testing for non-linear EKC-type behavior within the tourism sector. |
| Log-Transformed Variables | Natural logarithm applied to EF, T&T, GDP, EU, OT | | Ensures elasticity-based interpretation, reduces heteroscedasticity, and improves model fit. |
| Software & Tools | | | |
| Econometric Software | EViews / Stata / R (not specified but required) | | Used for time-series transformation, econometric estimation (ARDL, cointegration tests), diagnostics, and causality tests. |
| Econometric Methods & Tests | | | |
| Unit Root Testing | ADF, PP (implied), stationarity diagnostics for time-series | | Determines whether variables are I(0) or I(1) prior to ARDL estimation. |
| ARDL Bounds Testing | Pesaran et al. (2001) ARDL methodology | | Evaluates long-run cointegration among EF and its determinants; handles mixed orders of integration. |
| Fisher-Johansen Combined Cointegration Test | Engle–Granger, Johansen, Boswijk, Banerjee-Dolado-Mestre (BDM) | | Validates cointegrating relationships using multiple integrated cointegration statistics. |
| Long-run and Short-run ARDL Estimation | ARDL-based ECM framework | | Estimates short-run elasticities and long-run equilibrium relationships affecting EF. |
| Error Correction Term (ECT) | Derived from ARDL long-run equation | | Measures the speed at which EF returns to equilibrium after short-run shocks. |
| Structural & Stability Diagnostics | CUSUM and CUSUMSQ tests | | Tests for structural stability and absence of parameter shifts across time. |
| Causality Analysis | Granger causality (within ARDL framework) | | Determines directional causality between EF, tourism, GDP, EU, OT, and JV. |