Re: STUDENT REQUEST: Deming & performance appraisals

[DANSWART@aol.com]

In a message dated 04/12/2000 7:40:56 AM Pacific Daylight Time, WMack@pec.com 
writes:

<< 2) The average is almost a meaningless number for anything besides a 
normal distribution.>>
----------------------- SNIP

I understood that one purpose of the control chart is to put the average "on 
target," then strive to minimize variation around that mean, regardless of 
the distribution shape.  Is that too general a rule?
----------------------- 

<<  For example, a process with two parallel assembly lines may show two 
peaks for some value, one for each assembly line.  
 Neither assembly line may ever produce units with the average value.  The 
people on one line will be continually above average and those on the other, 
below.>>
 ------------------------ SNIP

If we observe a bimodal distribution shouldn't that alert us that our 
subgrouping, or grouping, may be inappropriate?  In the example given, 
shouldn't we track two such lines separately--then attempt to put the 
processes "on target, with minimum variation for each line?"
------------------------ 

<< 3) The control chart should be used to track the system.  By tracking an 
individual on the control chart, you have made the apriori assumption that 
the individual is the root cause of some problem....  
 
 If you have a system involving 100 people, it is highly unlikely that making 
changes to improve 1 person will affect the overall system measurably. It is 
much more effective to make changes that affect all, or a large number of the 
people in the system.>>
------------------------ SNIP

I understood that Dr. Deming thought it was fine to chart people, as 
individuals, on a control chart (isn't that what the Red Bead Experiment is?) 
as long as EVERYONE within the control limits is treated the same with 
respect to rewards/punishments/etc.  Those outside to the good side should be 
investigated for emulation and those outside on the bad side need special 
help. Saying one is "above average" is meaningless in such an analysis and is 
to be avoided.  Never should they be ranked.  The Red Beads teach us that 
today's "star" performer who is "above average," but within the control 
limits, may not be the "star" next week, or month, or year.  That is a 
difficult concept to accept.

It sounds like the original post wanted to differentiate someone one who's 
measurement is always above average, but within the control limits.  To the 
control chart experts:  would such a person be out of control on the "good" 
side?

If such a person charted their own performance on a control chart, and came 
to Dr. Deming and said, "See, my average performance is above the group 
average.  Don't I deserve a raise?" -- What would Dr. Deming say to that 
person?
------------------------------

<< I hope this helps.  The key is to focus on the upper and lower control 
limits and largely ignore the average. >>
-------------------------- SNIP

See questions above regarding average.


Dan
danswart@aol.com
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