USING SCIENTIFIC MEASUREMENTS Accuracy and Precision RHS Science Department.

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Accuracy and Precision

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USING SCIENTIFIC MEASUREMENTS Accuracy and Precision RHS Science Department

Whachathinkboutit? Write your definition of the following terms: Accuracy Precision Do they mean the same thing or is there a difference? If there is a difference, what is the difference? (Give an example.)

Accuracy vs. Precision To most people, the words Accuracy and Precision are synonymous. In the field of science, they have quiet distinct meanings. Accuracy is defined as the closeness of the measurement to the correct or accepted value of the quantity measured. Precision is defined as the closeness of a set of measurements of the same quantity to one another.

Accuracy

Precision

Whachathinkboutit? BOTH

Whachathinkboutit? NEITHER

Application of Concept Who is more accurate when measuring a book that has a true length of 17.0cm? Susan: 17.0cm, 16.0cm, 18.0cm, 15.0cm Amy: 15.5cm, 15.0cm, 15.2cm, 15.3cm

Application of Concept Who is more precise when measuring the same 17.0cm book? Susan: 17.0cm, 16.0cm, 18.0cm, 15.0cm Amy: 15.5cm, 15.0cm, 15.2cm, 15.3cm

Error Due to a variety of factors (eyesight, equipment limitations, material, etc…) there is a margin of error between our experimental measurement value and the accepted value. To calculate the error, we apply the following formula: Error = Value experimental - Value accepted

Percentage Error

Practice

Interpreting the Results Percent error can be positive or negative. If it has a positive value, it means that the experimental or measured value was greater than the accepted value. If it has a negative value, it means that the experimental or measured value was less than the accepted value.