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 light scattering are powerful techniques than are “resolution limited” compared to high resolution techniques which are based on particle counting (such as electro zone counting or image analysis). If the goal of the measurement is finding small populations of particles larger or smaller than the main distribution, then an investigation of the sensitivity to second distributions should be part of the selection process.