Beckman Coulter LS 13 320, User Manual

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PN B05577AC C-6
Optical Models
Statistics
The mean diameters (m.d.) represented by some choices of p and q are shown in Table C.1 , along
with the LS 13 320 software equivalent.
The default mean value in the LS 13 320 output is D(4,3).
Median and Mode
Median
The median is the particle diameter at which half of the distribution (half of the volume percent,
surface area percent, or number percent) is larger and half is smaller.
Mode
The mode is the value that occurs most frequently in a set of data. The value of the mode
corresponds to the channel center with the maximum volume percent, surface area percent, or
number percent, depending on the weighting chosen.
Characterizing the Distribution
The variance, standard deviation, coefficient of variation, confidence limits, skewness and kurtosis
characterize the shape of the particle size distribution. A normal distribution is symmetric in shape
in a linear horizontal axis and a log-normal distribution is symmetric in shape in a logarithmic
horizontal axis. Many statistical measurements use the normal curve or log-normal curve as a
reference.
Variance
Table C.1 Mean Diameters
D(p,q) Standard Name (LS 13 320 Program Equivalent)
D(0,0) Geometric mean diameter (Geometric mean size in Number % mode)
D(1,0) Arithmetic mean diameter (Arithmetic mean size in Number % mode)
D(2,2) Surface weighted geometric m.d. (Geometric mean size in Surface Area % mode)
D(3,2) Surface weighted m.d. (Arithmetic mean size in Surface Area % mode)
D(3,3) Volume-weighted geometric m.d. (Geometric mean size in Volume % mode)
D(4,3) Volume weighted m.d. (Arithmetic mean size in Volume % mode)
The variance is defined as:
Arithmetic