In this example, only one of the two variables
(self-esteem) is measured with numerical scores. In other situations,
when both variables are measured using numbers or ranks, a variety of terms
can be used to classify the relationships. For example, Figures 6.1(b) and
6.1(c) show linear relationships because the data points produced by the
changing values of the two variables tend to form a straight-line pattern.
Figures 6.1(d) shows an example of a curvilinear relationship. Again, there
is a consistent, predictable relationship between the two variables, but now
the pattern is a curved line. As we noted in Chapter 3 (p. 79), Figure 6.1(b)
and 6.1(d) are examples of positive relationships because increases in oneare discussed.