Focus on Global Terminology

 This month’s terms:

• Precision: closeness of agreement between independent test results obtained under stipulated conditions (ISO 3534-1)
• Repeatability: precision under conditions where independent test results are obtained with the same method on identical test items in the same laboratory by the same operator using the same equipment within short intervals of time. (ISO 5725-1:1994)
• Reproducibility: precision under conditions where test results are obtained with the same method on identical test items in different laboratories with different operators using different equipment. (ISO 5725-1:1994)
• Intermediate measures of precision: precision under conditions where test results are obtained within the same facility but under changed conditions of operator, equipment, or time. (adapted from ISO 3534-1); NOTE:  The changed conditions must be indicated.

NOTE: Repeatability is considered the smallest measure of precision, due to no changes in conditions (such as within-run precision), and reproducibility is considered to be the largest measure, with all test conditions changed (such as interlaboratory precision).  Intermediate measures (such as between-run precision, between-day precision, within laboratory precision, etc.) should lie between the extremes. 

For complete details on these and other internationally accepted terms, access NCCLS’s Harmonized Terminology Database.  In the database, find standard, internationally preferred terms and definitions, related terms, terms that are not acceptable in the international standards community, and illustrative notes and examples. [ return to top ]