  The equation for the size strain plot methods reported by A. Khorsand Zak et
al. (Solid State Sci. 13 (2011), 251) does not follow the dimensional
homogeneity, consequently leading to an inaccurate estimation of the
crystallite size and strain values of the materials under investigation and the
dimensions of the obtained parameters. We also perceived an error in the values
of crystallite size and strain reported by the authors using the size-strain
plot method. We will discuss the importance of dimensional analysis and its
repercussions on the estimated values and the units of parameters.
