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List of Standards

List of Standards

The list of standards (ASTM, BS and TCVN) which are commonly used in...

Holiday calendar in 2018

Holiday calendar in 2018

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Standard Penetration Test

Standard Penetration Test

Standard penetration test (SPT) is one of the most common in situ testing...

Precision or Accuracy ???

Precision or Accuracy ???

When working with technical documents, readers are often deal with specific...

Bulk Density

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1. Definition: A bulk density of a soil sample is defined as a mass per...

Compaction Test

Compaction Test

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On February 27, 2014, flatGEO Consulting Co. accessed to a webpage on...

Datalogger for Oedometers

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After a four-month-trial period, flatGEO has finished a datalogger system for...

  • List of Standards

    List of Standards

    July 18, 2011
  • Holiday calendar in 2018

    Holiday calendar in 2018

    October 2, 2011
  • Standard Penetration Test

    Standard Penetration Test

    December 12, 2011
  • Precision or Accuracy ???

    Precision or Accuracy ???

    January 7, 2012
  • Bulk Density

    Bulk Density

    February 20, 2012
  • Compaction Test

    Compaction Test

    March 7, 2012
  • Warning on Webpage Content Stealing

    Warning on Webpage Content Stealing

    February 27, 2014
  • Datalogger for Oedometers

    Datalogger for Oedometers

    July 21, 2015
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Accuracy or precision ?When working with technical documents, readers are often deal with specific terms “accuracy” and “precision”. The question is if these terms have the same meanings?

First of all, it is confirmed that the terms “accuracy” and “precision” are completely different. However because these terms are sometimes translated into Vietnamese using the same Vietnamese word so it makes readers confused.

The term “accuracy” is used to describe the difference between measured values with the "true" value or "referenced" value. Therefore, the term "accuracy" relates to the bias or system error of the measurement system.

The term “precision” is used to describe the closeness or the repeatability of measured values under the same measurement environment. Therefore, the term "precision" relates to the variation of measured values.

The dart board is often used to illustrate the difference between "accuracy" and "precision" (see figure below):

Comparison of

(Source: http://cwx.prenhall.com/bookbind/pubbooks/hillchem3/medialib/media_portfolio/01.html)

Figure a: Because three arrows are neither close to each other nor close to the bull's eye so this test is considered as low accuracy and low precision.

Figure b: Because three arrows are close to each other but not close to the bull's eye so this test is considered as low accuracy (too far from the "true" value -- bull's eye) and high precision (good repeatability).

Figure c: Because three arrows are not close to each other but close to the bull's eye so this test is considered as high accuracy (not far from the "true" value -- bull's eye) and low precision (bad repeatability).

Figure d: Because three arrows are not only close to each other but also close to the bull's eye so this test is considered as high accuracy and high precision.

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