http://www.ck12.org Chapter 3. Measurement
FIGURE 3.8
Lesson Summary
- Accuracy describes how close an estimate is to a known standard.
- Precision describes how close estimates are to one another.
- The accuracy of an estimate cannot be improved through calculation.
- Calibration is a technique used to standardize a measuring instrument and increase the accuracy of measure-
ments. - Estimation, as used in measurement, is the process of referencing a physical quantity in terms of a calibration
or reference point. All measurement devices have reference marks of some kind. - All measurements have an associated uncertainty. It is expressed as one-half of the smallest difference between
calibration marks. It can also be expressed as a percent. - Percent error is an expression of the accuracy of a measurement, standardized to how large the measurement
is. - Sources of error can originate from observation errors, methods or procedural errors, as well as errors associ-
ated with object that are measured. They can also originate from the measurement instrument itself. - Significant figures are figures associated with uncertainty of a measurement.
- Density is an expression of the mass of substance in terms of the volume occupied by the substance.