Accuracy and Precision

Measurement
In this article, we will see the difference between accuracy and precision terms. They are also most confusing terms in measurements regarding instruments.

Accuracy

Accuracy is the closeness with which the instrument reading reaches the true value of the quantity being measured.

 

  • The accuracy of measurement means conformity to truth.
  • The accuracy can be improved.
  • Accuracy simply depends upon the techniques of analysis.
  • Accuracy is necessary but not sufficient condition for precision.

 

Precision

Precision is a measure of reproducibility of the measurement, i.e. given a fixed value of a quantity or the degree of exactness for which instrument is designed or intended to perform.

 

  • Precise means clearly or sharply defined.
  • Precision cannot be improved.
  • Precision requires many sophisticated techniques of analysis.
  • Precision is necessary but not sufficient condition for Accuracy.

 

The difference between Accuracy and Precision can be better understood from below common example of target shooting experiment.

 

 

Excercise
Q1. Define Accuracy.
Q2. Define Precision.
Q3. Differentiate between Accuracy and Precision.
Q4. Explain with an example that accuracy can be improved while not the precision.

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