  We present a new approach to extract the power-law part of a
density/column-density probability density function (rho-pdf/N-pdf) in
star-forming clouds. It is based on the mathematical method bPLFIT of Virkar &
Clauset (2014) and assesses the power-law part of an arbitrary distribution,
without any assumptions about the other part of this distribution. The slope
and deviation point are derived as averaged values as the number of bins is
varied. Neither parameter is sensitive to spikes and other local features of
the tail. This adapted bPLFIT method is applied to two different sets of data
from numerical simulations of star-forming clouds at scales 0.5 and 500 pc and
displays rho-pdf and N-pdf evolution in agreement with a number of numerical
and theoretical studies. Applied to Herschel data on the regions Aquila and
Rosette, the method extracts pronounced power-law tails, consistent with those
seen in simulations of evolved clouds.
