Three Sources of Error

True error: Mistakes made in the measurement.

  • Ex: Experimenter reading a scale on a measurement incorrectly.

Random error: Result from limitations in the precision of the measurements.

Systematic error: Result from some bias in the way that the quantity is being measured.

  • Ex: Measuring a current with a ammeter that is not properly calibrated.

Accuracy vs Precision

Accuracy: How close the measurement is to some quantity.

Precision: Measure of how close repeated measurements are to one another.


Absolute Error

When we obtain a computed result x of some calculation and we wish to discuss its relationship with the correct mathematical result , we can measure either the absolute error:

Relative Error

The relative error is given by