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> This question is for those who have multiple instruments of the same model.
> Do you keep studies to one instrument, ie do you run all experiments for one
> study on the same instrument, or do you restrict them to one model? Does it
> depend on the experiment? Dye? I know you cannot compare data from two
> different models, but how comparable is data from the same model.
.
.
We have never had any qualms about comparing data from *very different*
instruments let alone the same model (like sorting on a FACS II and
analysing the sorted cells for purity on a FACScan), so long as we are
careful to characterize their relative performances.
One major problem is getting the logamps (assuming you're using them)
set to the same number of decades across the scale ( I say this
because our most recent 2 FACScans and 1 FACStar+ all had around 10%
more than 4 decades. Since the file headers all say 4 decades, if the
scales are not re-calibrated, any analytical software you use can give
you very erroneous answers even if you are *not* doing inter-model
comparisons. If you don't mind taking a screwdriver to the internals,
you can use Flow Cytometry Standards beads for the measurement. After
that, if you align a positive standard to any given channel on all
your machines, your scales will all be directly comparable for most of
their ranges. Your only remaining problem is at the low end and
that's where your different optical filter qualities, different
geometries, etc. will be reflected in different instrument background
levels. Since you will also be setting compensation between
fluorescence channels, the argument applies to each channel
independantly.
.. And also, Jack Dunne gives us:
> in flux veritas
Yes, maybe there is some "veritas" in those machines, but don't you
have to work real hard to get the "muther fluxers" to part with it.
.. And also, did everyone get duplicates of the last messages from
Trotter, Delohery and Bercz, or is that just *our* mail system??
Regards, | | < Frank: battye@wehi.edu.au
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