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Accuracy & Precision. Two important points in measurement. Accuracy. Accuracy = the extent to which a measured value agrees with a standard value Accuracy of a device must be checked Does it read a proper accepted value?
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Accuracy & Precision Two important points in measurement
Accuracy • Accuracy = the extent to which a measured value agrees with a standard value • Accuracy of a device must be checked • Does it read a proper accepted value? • Beware of Parallax – the apparent shift in position when viewed at a different angle.
Precision • Precision = the degree of exactness of a measurement that is repeatedly recorded. • Which set is more precise? 18.2 , 18.4 , 18.35 17.9 , 18.3 , 18.85 16.8 , 17.2 , 19.44 Set #1
Accuracy vs. Precision Accuracy = Low Precision = High
Accuracy vs. Precision Accuracy = Low Precision = Low
Accuracy vs. Precision Accuracy = High Precision = High