  Sigmoid semilogarithmic functions with shape of Boltzmann equations, have
become extremely popular to describe diverse biological situations. Part of the
popularity is due to the easy avail- ability of software which fits Boltzmann
functions to data, without much knowledge of the fitting procedure or the
statistical properties of the parameters derived from the procedure. The
purpose of this paper is to explore the plasticity of the Boltzmann function to
fit data, some aspects of the optimization procedure to fit the function to
data and how to use this plastic function to differentiate the effect of
treatment on data and to attest the statistical significance of treatment
effect on the data.
