It is important to emphasize that measures of center are not the only way to
characterize stable components of noisy processes. Both the shape of a frequency
distribution and global measures of variability, for example, also stabilize as we
collect more data; they, too, give us information about the process. We might refer
to this more general class of characteristics as signatures of a process. We should
point out, however, that all the characteristics that we might look at, including the
shape and variability of a distribution, are close kin to averages. That is, when we
look at the shape of a particular distribution, we do not ordinarily want to know
precisely how the frequency of values changes over the range of the variable.
Rather, we tame the distribution’s “bumpiness.” We might do this informally by
visualizing a smoother underlying curve or formally by computing a best-fit curve.
In either case, we attempt to see what remains when we smooth out the variability.
In a similar manner, when we employ measures such as the standard deviation or
interquartile range, we strive to characterize the average spread of the data in the
sample.
It is important to emphasize that measures of center are not the only way to
characterize stable components of noisy processes. Both the shape of a frequency
distribution and global measures of variability, for example, also stabilize as we
collect more data; they, too, give us information about the process. We might refer
to this more general class of characteristics as signatures of a process. We should
point out, however, that all the characteristics that we might look at, including the
shape and variability of a distribution, are close kin to averages. That is, when we
look at the shape of a particular distribution, we do not ordinarily want to know
precisely how the frequency of values changes over the range of the variable.
Rather, we tame the distribution’s “bumpiness.” We might do this informally by
visualizing a smoother underlying curve or formally by computing a best-fit curve.
In either case, we attempt to see what remains when we smooth out the variability.
In a similar manner, when we employ measures such as the standard deviation or
interquartile range, we strive to characterize the average spread of the data in the
sample.
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