Manual vs. Auto compensation
chen_li3 at yahoo.com
Sun Feb 10 10:36:43 EST 2008
Just a follow-up question about Maciej' graphs.
If I get some graphs showing either a little bit over
or under compensation similiar to those in Maciej's
graphs, how these are going to affect my final
analysis, compared to the perfect compensation one?
--- Maciej Simm <simm at treestar.com> wrote:
> It's very difficult to answer the question "should I
> do it by hand or
> computer" without the whole context of the specific
> scenario when one
> fails and the other works.
> Instead, we can focus on a broader question "is my
> Mathematically, we can estimate validity of our
> compensation matrices
> by comparing medians - for example, the median of
> the positives is
> equal to the median of the negatives. Medians are
> better than mean/
> GM's because they aren't affected by outliers and
> better represent
> central tendency of your data.
> Since biexponential transformation (aka logicle
> display, etc..) became
> popular in many software packages, there is an
> easier way to 'eyeball'
> bad compensation - enable this scaling and see if
> your single-
> negatives (some call them single-positives, I'm a
> sheath tank half-
> empty kinda guy ;) ) are symmetrically distributed
> around the X=0 /
> Y=0 lines similar to your double-negatives. If not,
> there's either
> over comp, or undercomp. Here's an example, with
> hypothetical X/Y
> parameter distributions:
> http://cd4cd8.com/1.png proper comp -1 % - the X+/Y-
> population leans
> upward, suggesting undercompensation.
> http://cd4cd8.com/2.png proper comp +1% - the X+/Y-
> population is
> sagging toward X axis. Over comp'd.
> http://cd4cd8.com/3.png proper comp (correct values)
> - the centers of
> X-/Y- and X+/Y- are aligned.
> hope this helps,
> Maciej Simm
> TreeStar Inc.
> PS. I vote for pistachio ice cream.
> >> I have people in the lab who complain about me
> not doing manual
> >> compensations and instead have the Aria calculate
> them for me. And
> >> when I have the Aria compensate, they want to
> manually compensate
> >> after they record the data because the plots
> "don't look right." I
> >> mean, isn't that simply producing "make-belief"
> data? Or am I
> >> missing something?
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