1.5. Working with Error http://www.ck12.org
1.5 Working with Error
Objectives
- Describe systematic and random error.
- Explain precision and accuracy as they relate to error.
Vocabulary
- accuracy
- precision
- random error:Error that varies within the inherent uncertainty of a measuring device.
- systematic error:An error of constant value that is made repeatedly.
Introduction
There is a difference between what we mean bymistakeanderrorin a laboratory setting. A mistake, for example,
is accidentally writing 3×5 = 8 rather than 15. On the other hand, a systematic erroris one of a constant value
that is made repeatedly.Random errorvaries within the inherent uncertainty of a measuring device: a meter stick
(±0.05 cm) or human reaction time (at worst±0.2 s). We will discuss both of these sources of error, along with
precisionandaccuracy.
The classic target example below is a good way of explaining precision.
- A data set can be precise, but inaccurate, as displayed inFigure1.10.
FIGURE 1.10
The hits are precise but inaccurate; they miss the center.- A data set can be imprecise, yet accurate, as displayed inFigure1.11.
- A data set can be imprecise, and inaccurate, as displayed inFigure1.12.
- A data set can be both precise and accurate, as displayed inFigure1.13.