In the field of observational methodology the observer is obviously a central figure, and close attention should be paid to the process through which he or she acquires, applies, and maintains the skills required. Basic training in how to apply the operational definitions of categories and the...

This study develops an innovated model of quantile regression model to portray a delicate relationship between per capita income and <InlineEquation ID="IEq4"> <EquationSource Format="TEX">$$\hbox {CO}_{2}$$</EquationSource> <EquationSource Format="MATHML"> <math xmlns:xlink="http://www.w3.org/1999/xlink"> <msub> <mtext>CO</mtext> <mn>2</mn> </msub> </math> </EquationSource> </InlineEquation> emission. The inclusion of the indicator of meta-technical ratio, generated from the directional distance function, not only...</equationsource></equationsource></inlineequation>