CH 104: Lesson 1a

Home Up Precision and Accuracy S. D. in Numbers Quick Quiz - Significant Digits S. D. in Calculations

 

Precision and Accuracy

Precision and accuracy are both important in chemistry. They are related, but they refer to different aspects of a measured or calculated value. Accuracy refers to how correct a value is. Precision refers to how many digits are used in the number.

The four values of pi in this table can be used as examples. Two values are accurate and two values are not accurate. In each pair one value is precise and one value is not precise.

Values of pi
  Precise Not precise
Accurate 3.14159 3.1
Not accurate 7.81713 7.8
 

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