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articles:optimizing_calibration_intervals [2019/03/17 18:22] – [Methodologies for the determination of calibration] rrandallarticles:optimizing_calibration_intervals [2019/03/17 18:33] – rrandall
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 <note>[[http://www.isgmax.com/|Integrated Sciences Group (ISG)]] offers a free "Method S2" interval calculator (for MS Windows only) augmented by the "Method A3 Interval Tester" (adjusting for "sparse" data) called [[http://www.isgmax.com/calint_freeware.htm|IntervalMAX]].</note> <note>[[http://www.isgmax.com/|Integrated Sciences Group (ISG)]] offers a free "Method S2" interval calculator (for MS Windows only) augmented by the "Method A3 Interval Tester" (adjusting for "sparse" data) called [[http://www.isgmax.com/calint_freeware.htm|IntervalMAX]].</note>
-===== The “Staircase” method ===== 
  
 Perhaps the simplest and most widely used methodology for optimizing calibration intervals is the "Automatic adjustment" or “Staircase” method (described in [[https://ilac.org/?ddownload=818|ILAC G24:2007, sec. 3, "Methods of reviewing calibration intervals"]]). Perhaps the simplest and most widely used methodology for optimizing calibration intervals is the "Automatic adjustment" or “Staircase” method (described in [[https://ilac.org/?ddownload=818|ILAC G24:2007, sec. 3, "Methods of reviewing calibration intervals"]]).
  
-==== How use it ====+===== Using the “Staircase” method =====
  
 Each time an instrument is calibrated on a routine basis, the subsequent interval is extended IF it is found to be within a certain percentage (e.g., 80%) of the maximum permissible error that is required for measurement, or reduced if it is found to be outside this maximum permissible error. \\ Each time an instrument is calibrated on a routine basis, the subsequent interval is extended IF it is found to be within a certain percentage (e.g., 80%) of the maximum permissible error that is required for measurement, or reduced if it is found to be outside this maximum permissible error. \\
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 A critical component when using this methodology is determining the percentage of the maximum permissible error. The higher the percentage, the greater the risk of an instrument being found Out-of-Tolerance (OOT); potentially resulting in nonconforming product escapes. The lower the percentage, the greater the cost associated with lowering the risk of an OOT condition; and reducing the potential for nonconforming product escapes. This percentage will often vary based upon the type of instrumentation to which it is applied. \\ A critical component when using this methodology is determining the percentage of the maximum permissible error. The higher the percentage, the greater the risk of an instrument being found Out-of-Tolerance (OOT); potentially resulting in nonconforming product escapes. The lower the percentage, the greater the cost associated with lowering the risk of an OOT condition; and reducing the potential for nonconforming product escapes. This percentage will often vary based upon the type of instrumentation to which it is applied. \\
  
-Most often companies establish a "range" for the optimization. For example, IF an instrument is found exceeding 75% of its maximum permissible error, then the calibration interval is shortened. However, IF an instrument is consistently found below 50% of its maximum permissible error, then the calibration interval is lengthened. And IF the instrument is found between 50% and 75% of it's maximum permissible error, then the interval is considered acceptable.+Most often companies establish a "range" (or "window) for the optimization. For example, IF an instrument is found exceeding 75% of its maximum permissible error, then the calibration interval is shortened. However, IF an instrument is consistently found below 50% of its maximum permissible error, then the calibration interval is lengthened. And IF the instrument is found between 50% and 75% of it's maximum permissible error, then the interval is considered acceptable.
 ===== Initial Calibration Intervals ===== ===== Initial Calibration Intervals =====