Manual vs. Auto compensation

chen li chen_li3 at yahoo.com
Sun Feb 10 10:36:43 EST 2008


Hi all,


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?

Thanks,

Li 


--- Maciej Simm <simm at treestar.com> wrote:

> Colleagues,
> 
> 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
> compensation	
> correct?"
> 
> 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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