Definitions

• Accuracy


  A measure of how close a measurement is to the true value
• Precision


  A measure of how close a measurement is to the mean value. It only gives an indication of the magnitude of random errors, not how close data is to the true value
• Random Error


  Unpredictable variation between measurements that leads to a spread of values about the true value. Random error can be reduced by taking repeat measurements
• Systematic Error


  Causes all readings to differ from the true value by a fixed amount. Systematic error cannot be corrected by repeat readings, instead a different technique or apparatus should be used
• Repeatable


  The same experimenter can repeat a measurement using the same method and equipment and obtain the same value
• Reproducible


  An experiment can be repeated by a different experimenter using a different method and different apparatus, and still obtain the same results
• Resolution


  The smallest change in a quantity that causes a visible change in the reading that a measuring instrument records
• Uncertainty


  The interval that a value is said to lie within, with a given level of confidence