Information Technology Reference
In-Depth Information
1000
500
0
Score
Figure 5.2
A positively skewed distribution.
5.3.1.2 Distributions Exhibiting Skewness
Skewed distributions are asymmetrical, with the most frequent scores
clustering around one of the ends of the distribution. Figure 5.2 depicts
a positively skewed distribution, where the scores are bunched around the
lower end; one way to remember a positive skew is that the “longer tail”
of the distribution is “pointed” toward the positive (right) side of the
x axis. Conversely, Figure 5.3 illustrates a negatively skewed distribution,
where the scores are concentrated on the high end. One way to remember
a negative skew is that the “longer tail” of the distribution is “pointed”
toward the negative (left) side of the x axis. As an organizing principle,
remember this mnemonic device: “the tail tells.”
5.3.1.3 Distributions Exhibiting Kurtosis
Kurtosis refers to the relative “peakedness” or “flatness” of the scores in
a distribution. Figure 5.4 depicts a leptokurtic distribution, which tends
to have tails that are higher than the normal curve is and bunched in the
Search WWH ::




Custom Search