3.3. Uncertainty in Measurements http://www.ck12.org
3.3 Uncertainty in Measurements
Lesson Objectives
- Distinguish between accuracy and precision in measurements.
- Calculate the percent error of a measured quantity.
- Report measured values to the correct number of significant figures based on the measuring tool.
- Perform calculations with measured quantities, rounding the answers to the correct number of significant
figures.
Lesson Vocabulary
- accepted value
- accuracy
- error
- experimental value
- percent error
- precision
- significant figures
Check Your Understanding
Recalling Prior Knowledge
- Suppose that a baseball pitcher throws very accurately. What does that mean? Is it different from throwing
very precisely? - When you make a measurement with a specific measuring tool, how well can you read that measurement?
Will individual measurements have an affect on quantities that are calculated from those measurements?
When making a measurement, there is always going to be some uncertainty. Some of that uncertainty is related to
the reliability of the measuring tool, while some of it is related to the skill of the measurer. When you are performing
measurements, you should always strive for the greatest accuracy and precision that you possibly can (Figure3.7).
Accuracy and Precision
In everyday speech, the terms accuracy and precision are frequently used interchangeably. However, their scientific
meanings are quite different.Accuracyis a measure of how close a measurement is to the correct or accepted value