An analyst's guide to precision.

Area of Science:

• Analytical Chemistry
• Metrology

Background:

• Precision is a key concept in analytical chemistry, defined by the VIM3 (International Vocabulary of Metrology).
• The VIM3 defines precision as the closeness of agreement between replicate measurements under specified conditions.
• However, precision itself is not directly quantified in this definition.

Purpose of the Study:

• To clarify the definition and quantification of precision in analytical chemistry.
• To distinguish precision from standard deviation.
• To emphasize the importance of accurate terminology in scientific writing.

Main Methods:

• Review of the VIM3 definition of precision.
• Analysis of the relationship between precision and standard deviation.
• Discussion of practical implications for analytical chemists.

Main Results:

• Precision quantifies the agreement between measurements, not their scatter.
• Standard deviation measures dispersion, which is inversely related to precision.
• Using precision and standard deviation interchangeably can lead to misunderstandings.

Conclusions:

• Precision and standard deviation are distinct concepts in metrology and analytical chemistry.
• Standard deviation quantifies dispersion, while precision describes measurement agreement.
• Careful use of terminology is essential for clear scientific communication.