The Science of Physics

The Science of PhysicsSection 1-2Accuracy vs. Precision

AccuracyAccuracy is the agreement of a measurement with the accepted value.

Error is usually associated with accuracy.Human errorMethod errorInstrument errorErrors can often be corrected.

PrecisionPrecision of a measurement tells how close several measurements of the same quantity are to each other.Precision also deals with how exact a measurement can be.

Uncertainty is usually associated with precision.

Example: A metric stick marked off with smallest units of cm is less precise than one marked off in mm.

Example 1Data Set A: 0.8888 g0.9959 g1.1182 g1.0033 g0.9938 g1.0000 g--average

Data Set B:1.3110 g1.3109 g1.3111 g1.3110 g1.3110 g1.3110 g--averageActual Mass: 1.0000g Good/poor accuracy? Good/poor precision?

Example 1Data Set A: 0.8888 g0.9959 g1.1182 g1.0033 g0.9938 g1.0000 g--average

Data Set B:1.3110 g1.3109 g1.3111 g1.3110 g1.3110 g1.3110 g--averageActual Mass: 1.0000g Good/poor accuracy? Good/poor precision?

Example 2In this example there are 2 sets of data for the 5 measurements of the length of a stick.Which set of data is more precise?Data Set A: 1.1 m1.2 m1.1 m1.1 m1.2 m

Data Set B:1.12 m1.12 m1.11 m1.10 m1.13 m

Example 2The range of measurements for data set A is 0.1 m. The range of measurements for data set B is 0.03 m. Thus data set B is more precise.Data Set A: 1.1 m1.2 m1.1 m1.1 m1.2 m

Data Set B:1.12 m1.12 m1.11 m1.10 m1.13 m

Sources for more helphttp://www.youtube.com/watch?v=5APhVxCEPFs

http://www.youtube.com/watch?v=3G5IWRDfgTw