Accurate or Precise Creating definitions and clarifying terms

Accurate or Precise? Creating definitions and clarifying terms

Precision • precision is the ability to repeat a measurement and come up with the same value. • it is an indication of how close a series of measurements are to each other. • the idea of precision is very closely aligned with the idea of significant figures.

Precision • a large number of significant figures suggests a high degree of precision.

Accuracy • an indication of how close a value is to the real value (often theoretical) • often presented in terms of Relative Error (RE) • Relative error shows how far a measured value is from the actual value. • it is expressed as a percent and is calculated as follows:

RE (measured value - accepted value) = accepted value x 100%

Accurate or Precise? Case 1 • In the diagram, what can we say about the group of arrows in terms of accuracy: precision:

Accurate or Precise? Case 1 • In the diagram, what can we say about the group of arrows in terms of accuracy: low (as a group) precision: low

Accurate or Precise? Case 2 • In the diagram, what can we say about the group of arrows in terms of accuracy: precision:

Accurate or Precise? Case 2 • In the diagram, what can we say about the group of arrows in terms of accuracy: low precision: high

Accurate or Precise? Case 3 • In the diagram, what can we say about the group of arrows in terms of accuracy: precision:

Accurate or Precise? Case 3 • In the diagram, what can we say about the group of arrows in terms of accuracy: high precision: high

Accurate or Precise? • In summary: • Precision is connected to significant figures • Accuracy is connected to relative error