measured by the American standard. However, the pattern changes by the
age of 15 years when their average height drops to a level below the 5th per-
centile. In this example, we plot theaverageheight of five girls instead of indi-
vidual heights; because the Hmong are small, individual heights are likely to be
o¤ the chart. This concept ofaverageormeanis explained in detail in Section
2.2.
2.1.5 Stem-and-Leaf Diagrams
A stem-and-leaf diagram is a graphical representation in which the data points
are grouped in such a way that we can see the shape of the distribution while
retaining the individual values of the data points. This is particularly conve-
nient and useful for smaller data sets. Stem-and-leaf diagrams are similar to
frequency tables and histograms, but they also display each and every obser-
vation. Data on the weights of children from Example 2.2 are adopted here to
illustrate the construction of this simple device. The weights (in pounds) of 57
Figure 2.8(Continued)70 DESCRIPTIVE METHODS FOR CONTINUOUS DATA