Building on the Kumar and Russell (2002) methodology, we propose a conditional frontier approach which allows singling out the role of technology gap in explaining labour productivity differences. We find convergence in labour productivity growth driven by capital accumulation and technical...

Kao (2012) proposed a method to decompose DMU efficiency into sub-unit efficiencies for parallel production systems. We provide a numerical example showing that the proposed method can yield negative sub-unit efficiency scores under variable returns to scale, against common sense and standard...