On occasion, out-of-tolerance UUT (unit under test) parameters are erroneously observed to be in-tolerance during testing or calibration.  If such parameters are not adjusted, they will be deployed in an out-of-tolerance condition.  The risk that this will occur is called false accept risk.  ISG is pleased to offer a comprehensive measurement decision risk freeware application for analyzing false accept risk.

RiskGuard 2.0 provides both "program-level" and "bench-level" analyses of false accept risk to facilitate compliance with ANSI/NCSL Z540.3.  Program-level analysis determines false accept risk for routine tests or calibrations and develops guardband limits that can be applied in test or calibration procedures, as an accompaniment to parameter tolerance limits.  In bench-level analysis, the decision to adjust or otherwise correct the value of a unit under test (UUT) is made in response to an entered measurement result and measurement process uncertainty.

 Last Software Revision: 2/6/2012

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Statistical process control (SPC) can be employed to monitor a measurement process to ensure that risks are controlled to an acceptable level. In exercising this control, the process is checked from time to time by applying it to the measurement of a reference standard, referred to as a “check standard.” The difference between the assumed value of the standard and the measured value constitutes a deviation that can be plotted over time to maintain a control history, i.e., to verify whether it lies within a set of control limits.
 
Establishing control limits for a measurement process that is used to test or calibrate a given UUT parameter should be done in such a way that the maximum allowable difference between an assumed and a measured check standard value is consistent with a maximum allowable level of risk in testing or calibrating the parameter. Control limits established in this way are called risk-based limits.

SPCLimits develops control limits that are keyed to a specified acceptable level of measurement decision risk that would be present if the measurement process is used to test or calibrate a specific device parameter.

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