Degree of persistence of energy mix diversification of the US states: fresh evidence using LM unit root tests with sharp or smooth breaks and cross-sectional dependence.

Diversification of energy mix is related to the heterogeneity of contributions of energy sources in the energy consumption basket of nations. Its persistent degree reveals the efficiency of energy-related policies or shocks to diversify the contributions of energy sources in the energy mix. For the first time, the current study measures the diversification level of energy mix of the USA and its 51 states and examines its stochastic behavior to analyze its degree of persistence.

Does tourism market diversification matter for CO emissions? evidence from Singapore.

This research analyzed the effect of tourism market diversification on Singapore's CO emissions by measuring the level of concentration of source countries in a foreign tourist basket of Singapore using a Herfindahl-Hirschman index. Our results indicated that the index fell over the period 1978-2020, which means the diversification of source countries of Singapore's foreign tourists increased. By applying the recent bootstrap and quantile ARDL models, we found that tourism market diversification and inward FDI act as stumbling blocks to CO emissions.