Variation of powder-diffraction peak shapes caused by structural imperfections, e.g. by strains or stacking disorder, in crystalline solids can usually be described analytically. However, a precise and versatile analytical description, which adequately models the influence of all possible types of disorder, is hardly feasible. We present an alternative method of interpretation of peak-shape variations in powder patterns. This approach does not use analytical descriptions of any kind and, as a consequence, avoids usually inevitable approximations. It is based on the use of the general equation of Debye. Any type of disorder can be easily introduced in the ideal structure by changing the coordinates of atoms in the scattering domain. The use of this approach to the peak-shape analysis is illustrated by several examples.