C-Therm Blog

Understanding the Difference Between Accuracy and Precision

Accuracy and precision are often confused.  It is important to understand the difference between the two and how it applied to assessing the peroformance of thermal conductivity instrumentations such as the C-Therm TCi Thermal Conductivity Analyzer.

ACCURACY
Accuracy refers to the closenessof a measured value to a standard or known value.  In thermal conductivity, accuracy of a given technique or method is tyipcally assessed in testing a known standard reference materials as provided by organizations such as the National Physical Laboratory (NPL)  in the UK or the National Institute of Standards and Technology (NIST) in the USA.  Such reference materials provided by NPL or NIST are well-characterized and have generally-accepted values for the thermal conductivity of the material.  

PRECISION
Whereas precision refers to the closeness of two or more measurements to each other (please refer to the Figure 1). The accuracy reflects the systematic error, while the precision indicates the level of random error.  Precision can be assessed without the need of a certified reference standard accordingly.  

Accuracy and Precision

 

As NIST states; In general, a Standard Reference Material®1 (SRM) issued by the National Institute of Standards and Technology (NIST) is a homogeneous and stable material which is measured accurately and certified as a reference material for purposes of evaluating a measurement process. Standard Reference Materials are provided by NIST as primary tools to assist user communities in achieving measurement quality assurance and metrological traceability. These materials are used by industry, academia, and government to verify or improve the accuracy of specific measurements and to advance the state-of-theart knowledge.

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