http://www.ck12.org Chapter 1. What Is Science?
FIGURE 1.11
The average of the hits is fairly accurate, but the shots are imprecise.FIGURE 1.12
The shots are imprecise and they miss the mark.FIGURE 1.13
Both precision and accuracy are apparent.Defining Error
The error that generates a precise but inaccurate result is typically associated with systematic error. Systematic error
is usually a result of an error of calibration, like a scale that is not zeroed. A nurse’s aide recording the weights of a
group of toddlers may not realize that the scale reads two pounds before any weight is placed on it. Therefore, each
toddler’s weight appears two pounds greater than it really is (seeFigure1.14). Systematic error is detected when
an ordered pair of data should have a direct relationship (the function should pass through the origin of a Cartesian
coordinate system) yet does not by a greater uncertainty than the measuring tool suggests. In general, this kind or
error can be corrected by a constant shift in the data.
Random error generally refers to the limits of the equipment and people involved in an experiment. It does not mean
that such an error is necessarily correctable.
Consider the example below: