PRISM Forum - Message Replies


Topic: PRISM Questions and Answers
Topic Posted by: SRC (src_forum@alionscience.com )
Organization: SRC
Date Posted: Wed Jan 12 8:33:33 US/Eastern 2000
Topic Description: Welcome to the PRISM forum! Please feel free to post your questions and comments about the PRISM assessment software here.

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Original Message:

Posted by: Don Alderman (dalderma@ball.com )
Organization:Ball Aerospace
Date posted: Fri Jun 2 12:20:39 US/Eastern 2000
Subject: Process Grading
Message:
We have purchased the PRISM program and are currently trying to evaluate the approach for process grading. Some questions and concerns have come up: 1. Apparently only the questions with asterisks have to be answered. Please confirm. 2. Assuming 1. above is true, it seems the process grading could be subject to unscrupulous users wanting to get the competitive edge. The questions without asterisks could be "cherry picked" to increase the process score. If this is true, are we in a numbers game? 3. How do we find the "default" process grading pi factor values? The documentation only says they are "average" values.


Reply:

Subject: Process Grading
Reply Posted by: David Dylis (ddylis@alionscience.com )
Organization: Reliability Analysis Center (RAC)
Date Posted: Mon Jun 5 10:04:12 US/Eastern 2000
Message:
Process-related variability around an assembly or system failure rate is implemented within PRISM via a methodology called Process Grade Factors. By answering a series of questions within a specific grade type, the user establishes a scoring profile whose total value is translated into a quantitative pi-factor multiplier for that type that impacts the predicted failure rate. Process grade types currently defined within PRISM are: Design, Manufacturing, Parts Quality, System Management, CND, Induced, Wearout, Growth and Infant Mortality. This grading is accomplished by assessing the processes in a self audit-like fashion. Any or all of these process grade types can be assessed and graded. If the user chooses not to address a specific process grade, the model simply reverts to the default “average” value. If the user chooses to apply the grading methodology for any process grade, there is a minimum number of questions that must be assessed and graded. As you mentioned, these are marked with an asterisk. Beyond this minimum, the user can selectively assess and grade additional criteria. If answers to the grading questions are not known, the model simply ignores that criteria. The RAC purposely allowed for a user to selectively choose questions beyond those that are required, since information for specific process grade questions may not be readily available to the analyst. As in any analysis, users may not be truthful and either not input available information or provide errant information. No one can stop someone from cheating…. It is, however, recommended that users supply supporting information to back their process grading claims. As for how to determine default Pi factor values, create a new process grade set and name it “default”. Save this new set without assigning any previously defined individual process grade types that make up the process grade set. This will create a default process grade set with defaults for each of the process grade types that make up a process grade set.


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