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I am curious how people have dealt with the issue of variance in  
positional measurement ( using the measuring tool in ImageJ, for  
example) and its contribution to particle speed measurements.  The  
positional variance produces paradoxical "speed" for non moving  
particles - if particle displacement is determined between successive  
images. This effect directly increases with sampling frequency.

I have looked at a number of papers on cell migration and not found a  
correction or mention of this effect - which can be large for high  
sampling frequencies.
One idea would be to define a minimum detectable displacement based  
on the standard deviation of the measurement.  Every value less than  
that minimum would be set to zero???

Thanks,
Eric


Eric C. Olson, PhD
Assistant Professor
Department of Neuroscience and Physiology
SUNY Upstate Medical
3295 Weiskotten Hall
766 Irving St.
Syracuse, NY 13210

office: 315-464-7776
lab    : 315-464-8157