Particle size distribution is sufficient information for the majority of particle characterization applications. But some techniques are higher resolution than others. Ensemble technologies such as laser diffraction and dynamic lightscattering are powerful techniques than are “resolution limited” compared tohigh resolution techniques which are based on particle counting (such as electrozone counting or image analysis). If the goal of the measurement is findingsmall populations of particles larger or smaller than the main distribution, thenan investigation of the sensitivity to second distributions should be part of theselection process.