Hi Werner,

I did sort of the same thing. I took some CCA's and had the inspector's
arrow all the "defects". I photocopied the boards, removed the
inspection arrows and repeated it twice for each inspector, each time
having them think it was a different assembly.

Not only was the difference between each inspector amazingly different
but the difference from what the same inspector saw the first time
through was an eye opener.

It would be fun to try the same experiment using the same assembly at
different times of the day. I'll bet the one inspected near going home
time would have a lot fewer arrows than the one in the morning.

KennyB

-----Original Message-----
From: Werner Engelmaier [mailto:[log in to unmask]] 
Sent: Thursday, January 11, 2007 11:52 AM
To: [log in to unmask]
Subject: Re: [TN] Manual Visual Inspection of PCB Assemblies

Hi Bob,
There is the 'old' Western Electric study-I do not know whether it ever
was 
published externally [Lee do you know?], where 4 inspectors [some
actually 
inspector trainers] were given 4 assemblies [actually only 2 but each
inspected 
twice without them knowing it] to inspect as to whatever criteria were
deemed 
important at that time [ca. 1970's]. The agreement for all these
inspections 
amounted to a whopping 4%.

Werner

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