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A microcomputer spreadsheet technique for analyzing multimodal particle size distributions.
Hewett P; McCawley MA
Appl Occup Environ Hyg 1991 Oct; 6(10):865-873
Multimodal particle size distributions (PSD) were analyzed using a microcomputer spreadsheet technique for fitting a smooth curve to a size distribution having underlying modes. Estimates of the parameters of the underlying distributions, geometric means (GM), geometric standard deviations (GSD), and the percentage each underlying distribution contributes to the overall distribution were also provided by the technique. A contrast was indicated between this technique and interpretations of PSDs by single GMs and GSDs using log probability or probit analysis. Development of the smooth curve fit to a histogram required that the histogram be calculated and graphically displayed; that the number of underlying distributions, the GM and GSD of each distribution, and the percent contributions be estimated visually; that the smooth multimodal distribution frequency curve be calculated according to the estimates made and then superimposed upon the histogram; and that estimates pertaining to the underlying distribution parameters be changed to create a satisfactory fit. The author cautions that before parameter estimates are made for the underlying distributions, the existence of modes and underlying distributions should be checked through use of multiple samples, source assessment and corroboration using different measuring devices.
NIOSH-Author; Computer-models; Mathematical-models; Analytical-models; Analytical-methods; Biostatistics; Statistical-analysis; Biological-distribution; Aerosol-particles
Issue of Publication
Applied Occupational and Environmental Hygiene
Page last reviewed: September 11, 2020
Content source: National Institute for Occupational Safety and Health Education and Information Division