Appeal No. 1998-3339 Page 3
Application No. 08/614,459
there has been a significant change in the typical reject rate
compared with the expected situation. Accordingly, action can
be taken to identify the cause of the change and procedures
can be put in place to correct the problems, i.e., to return
the reject rate to the expected position.
Claim 1, which is representative for our purposes,
follows:
1. A method of carrying out reject analysis on
a process, the method comprising the steps of:
a) defining a set of reject classifications for
products produced by the process;
b) sampling data relating to rejected products
obtained from the process for the defined set of
reject classifications;
c) defining a model of the process from the
sampled data;
d) applying limits to the model indicative of
out-of-control conditions;
e) monitoring the process for out-of-control
situations; and
f) taking corrective action to bring the process
back into control when the applied limits have been
exceeded;
characterized in that the model is defined using
principal component analysis in terms of the
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