A Note On PCIs, Truncated Normal Variates, and Balanced Subintervals of a Tolerance Window

If inspection shows that a collection of parts does not conform to the design
specification, in traditional design a conforming subcollection can be culled
by screening to the worst-case tolerance window. If a part is statistically
specified, this approach need not be successful. However, if one assumes
specification by process capability indices, assumes part values to be normally
distributed, and obtains explicit formulas for means and variances of truncated
normals, then a maximal balanced subinterval that is conforming can be found.
This report documents this process.

By: Michael A. O'Connor, Vijay Srinivasan

Published in: RC20860 in 1997


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