The shape of the distribution
We can tell something important about the data by looking at the
overall shape of the distribution. For example, we sometimes find that
a frequency polygon yields the familiar bell-shaped curve.
Table 5.6
An example of a symmetrical distribution.
In this distribution, most of the cases are in the middle, around the
central tendency in the distribution (more about central tendency
later). There are only a few cases at either extreme.
If there are a few cases at one extreme, we call the distribution
skewed. If the extreme cases are at the positive end of the
scale, with larger values, then the distribution is said to be
positively skewed.
Table 5.6
An example of a positively skewed distribution.
If the extreme cases are at the negative end of the scale, with smaller
values, the distribution is negatively skewed.
Table 5.7
An example of a negatively skewed distribution.
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