5 Best Calibration Interval Guides


Recently, there have been a lot questions and discussion regarding calibration intervals. People want to know how to establish and adjust calibration intervals appropriately. Well, there is not one single method that will apply to all or most situations. Therefore, I recommend that you study as many methods of Calibration Interval Analysis as possible to learn which will best apply to your specific requirements. So, I have put together a list of papers and guides related to calibration interval analysis. I hope it will help you chose the method or methods that will work best for you.


My Top 5 Recommended Documents

1 | ILAC G-24: Guidelines for the Determination of Calibration Intervals
The ILAC G24 guide is the first document that I recommend you read. It provides guidance that is internationally accepted for compliance with the ISO/IEC 17025:2005 standard. Not only does it outline guidance for compliance, but it provides insight into the establishment of calibration intervals and five methods for the adjustment of calibration intervals.


2 | NCSL RP1: Establishment and Adjustment of Calibration Intervals
The NCSL International RP-1 publication is probably the most recognized, referred, and referenced document for the establishment and adjustment of calibration intervals. This is why it is second on my list. The publication is the most comprehensive and contains several methods for adjusting calibration intervals. Some are simple, while others are more complex. However, it is not free. The NSCLI RP-1 will cost you $75, but it is well worth the price tag.
The link below will take you to the NCSLI website, where you can read more about the RP-1 publication and purchase the document if you like.


3 | Simplified Calibration Interval Analysis
The paper was presented at the 2006 NCSL International Workshop and Symposium in Nashville, Tennessee.  I recommend this paper because it provides a simple algorithm for adjusting calibration intervals based on an instrument’s history of calibration performance. Although other methods use historical data, this method is simple and quick to use. No engineering degree required.


4 | Cost Effective Calibration Intervals
This paper was presented at the 1995 ASQC Annual Quality Conference in Cincinnati, Ohio. The method described in this paper uses the Weibull probability distribution to characterize failure data to estimate calibration intervals that minimize risk and cost. I recommend this paper because this methods aims to satisfy the business and quality goals of an organization. For me, that is win-win.


5 | Calibration Intervals from Variables Data
This paper was presented at the 2005 NSCLI Workshop and Symposium in Washington, D.C. Furthermore, it was published in Measure Magazine in 2006. The methods described in this paper show how to determine calibration intervals using variability data and regression analysis (my favorite!). I recommend this method for engineers and persons with a mathematical background in statistics. If this is not you, you may find the methods described more complex than the others.


Other Recommended Articles

The following papers and presentations did not make my top 5 list, but are definitely honorable mentions for those exploring more about calibration interval analysis. Therefore, check out the information below; I hope that is beneficial to your enlightenment. If you have any suggested documents or information that you believe that I should add to this list, please email me at rhogan@isobudgets.com.


Oak Ridge National Laboratory – Calibration Interval Technical Basis Document

NIST GMP-11 – Assignment & Adjustment of Calibration Intervals for Laboratory Standards

Single-use Calibration Intervals

Reliability Analysis Methods for Calibration Intervals

Managing Calibration Intervals

Techniques for Optimizing Calibration Intervals

Calibration Intervals: A Manufacturer’s Perspective

Determining Calibration Intervals for Process Control Instruments

Calibration Interval Adjustment Methods Programmatic Cost Effects

Frequency of Calibration

UL Equipment Calibration Intervals

Troemner – Determining Weight Calibration intervals

Beamex – How often should Instruments be calibrated?

Tangent labs – Choosing a Calibration Interval

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About the Author

Richard Hogan

Richard Hogan is the CEO of ISO Budgets, L.L.C., a U.S.-based consulting and data analysis firm. Services include measurement consulting, data analysis, uncertainty budgets, and control charts. Richard is a systems engineer who has laboratory management and quality control experience in the Metrology industry. He specializes in uncertainty analysis, industrial statistics, and process optimization. Richard holds a Masters degree in Engineering from Old Dominion University in Norfolk, VA. Connect with Richard on Google+ and LinkedIn.

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