  Labour productivity distribution (dispersion) is studied both theoretically
and empirically. Superstatistics is presented as a natural theoretical
framework for productivity. The demand index $\kappa$ is proposed within this
framework as a new business index. Japanese productivity data covering
small-to-medium to large firms from 1996 to 2006 is analyzed and the power-law
for both firms and workers is established. The demand index $\kappa$ is
evaluated in the manufacturing sector. A new discovery is reported for the
nonmanufacturing (service) sector, which calls for expansion of the
superstatistics framework to negative temperature range.
