[MLB-WIRELESS] Anecdote warning (was Why the big ...)

[Toliman]

At 12:44 PM 19/08/2002, you wrote:
>"quiet everybody, an old man is about to tell a story..." :-)
>
>vak wrote:
>
>>4/800 = 0.00571 % failure rate.
>
>it has been common policy for a lot of hardware manufacturers to specify a 
>maximum failure rate, usually specified as n/m, where n is say 3 and m is 
>say 10000.

I think it's more likely to be related to an (industrial) engineering term 
for Quality Control and Assurance called six-sigma, where you provide 
reliability for up to 99.9997% of the manufactured parts (in a quirky 
logarithmic function of produced parts versus defects or failures in the 
manufacturing process). Six Sigma is a goal of industry production 
processes to reduce defects in manufacturing to a level of 1or 2 defects 
for every million parts produced. Three-sigma is roughly 94% of the total 
production reliability, which is considered the minimum for industrial 
processes.

for 10,000 parts, having 3 defects is around 5 sigma. which also equates to 
99.98% reliability of processed parts. or a 0.0003% failure rate. sometimes 
signifying a high quality control value also forces contractors to follow 
stricter guidelines and delivery/quality control agreements or face 
penalties. etc.


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