CV question

Michal Bochenek mbochen at
Thu Sep 7 00:11:47 EST 2000

> There is an effect that has been observed regarding the CV of 2.5 micron
> calibration beads using on a flow cytometer. When the peak channel is
located at
> lower channel numbers the CV is increased. i.e. the CV of a population is
> at mean channel 100 ( 2.41)  than at mean channel 800 ( 1.25). What is the
> statistical explanation for this phenomenon.

Hello Robert,
Statistics for a histogram are calculated as follows:

CV = (SD/Mean) x 100
where Mean = [SUM(channel number x count in the channel)]/total number of
cells in the region.

So higher channel numbers give higher Mean and - finally - lower CV. I think
it works for any kind of particles.
I hope this helps you.
Best regards,

Michal Bochenek, PhD.
mbochen at
National Research Institute for Animal Production
Dept. of Animal Reproduction
32-083 Balice/Krakow, Poland
ph. (48 12) 2856777 ext. 145
fx.  (48 12) 2856733

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