Using the recently developed linearity test and non-linear unit root test, this study shows that the income gaps of Finland, Norway and Sweden with respect to Denmark are non-linear but stationary with no significant trend effect, implying the Nordic countries have already attained steady state...

Using the recently developed linearity test and nonlinear unit root test, this study shows that the income gaps of Finland, Norway, and Sweden with respect to Denmark are nonlinear but stationary with no significant trend effect, implying the Nordic countries have already attained steady state...