FW: rare event

From: Leary, James F. (jleary@utmb.edu)
Date: Fri Dec 03 1999 - 12:47:35 EST


Flow group, and particularly for those of you who have called since my
previous posting, my apologies. The correct reference should be: Rosenblatt,
J.I., Hokanson, J.A., McLaughlin, S.R., Leary, J.F.:  "A
Theoretical Basis for Sampling Statistics Appropriate for the Detection and
Isolation of Rare Cells Using Flow Cytometry and Cell Sorting"  Cytometry
27: 233-238, 1997. In addition to rare cell sampling statistics this paper
provides a perspective on the tradeoffs inherent in high-speed flow
cytometry and cell sorting, and attempts to provide some advice on how fast
is fast enough depending on what you are trying to do. It also provides some
useful advice as to how stable the statistics are for small numbers of
cells, since Poisson statistics are only an approximation that is not always
accurate. While we present some mathematics for the "hard core" groups out
there, we also provide some easy to interpret graphs to quickly and visually
present the important take-home messages. If you find this useful (or not)
please let me know. The only way we learn is to share experiences, and we
very much want our work to be useful to others. These take-home messages
really work in the practical world. We have found them very useful for
guiding our own work as we develop a number of new
high-throughput/rare-event applications. -- Jim Leary

-----Original Message-----
From: Leary, James F. [mailto:jleary@UTMB.EDU] 
Sent: Thursday, December 02, 1999 2:14 PM
To: cyto-inbox
Subject: RE: rare event



Hai -- You might find our paper on rare cell sampling statistics helpful
(Rosenblatt, J.I., Hokanson, J.A., McLaughlin, S.R., Leary, J.F.:  "A
Theoretical Basis for Sampling Statistics Appropriate for the Detection and
Isolation of Rare Cells Using Flow Cytometry and Cell Sorting"  Cytometry
26: 1-6; 1997).   -- Jim Leary

-----Original Message-----
From: Qi, Hai [mailto:haqi@UTMB.EDU]
Sent: Wednesday, December 01, 1999 4:49 PM
To: cyto-inbox
Subject: rare event




It is really not too rare, a cell population about 0.04% to 0.15%, while the
background is 0.01-0.05%. The problem is the variation among different
measurements, presumably due to the systematic error. For example, I had
10e7 total cells and ran 2*10e5 out of them for two times: one time I got
0.04% and the other time I got 0.15%. In order to have smaller variation,
obviously I have to increase my sample size, but the last thing I want to do
is to run through all 10e7 cells. Can anyone give me a handy statistical
method for estimating the sample size that makes a cost-effective
compromise? Thank you very much.

Hai Qi
Dept. of Pathology, UTMB



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