z-average

From the first letter of the German word Zentrifuge (centrifuge), because this measurement was first used with centrifugation data.

z-average (plural z-averages)

1. A weighted average where the value for each component is weighted by the square of its mass or volume.
   • 1984, Howard G. Barth, Modern Methods of Particle Size Analysis, →ISBN, page 113:

     When proper measurements are made, the parameters of the size distribution most often obtained -- the inverse z-average moments -- are not the usually reported parameters of a size distribution.

   • 1995, S. R. Holding, E. Meehan, Molecular Weight Characterisation of Synthetic Polymers, →ISBN, page 4:

     The calculated number average molecular weight is generally very dependent upon the low molecular weight material in the distribution, whilst the z-average is more affected by the high molecular weight material present.

   • 2007 -, Wolfgang Schärtl, Light Scattering from Polymer Solutions and Nanoparticle Dispersions, →ISBN:

     The harmonic average lies in between the z-average and the weight-average particle size.

The term z-average is used primarily in the context of light scattering or centrifugation measurements.