If variables x and y

move up and down together, they are positively related.

Demonstrating how an economic variable changes

from one year to the next is best illustrated by a time-series graph.

For a straight line,

if a large change in y is associated with a small change in x, the line is

steep.

The slope of a curved

line is not constant.

Graphing things that

are unrelated on one diagram is not possible.

If the graph of the

relationship between two variables slopes upward to the right, the relationship

between the variables is positive.

The slope of a

straight line is calculated by dividing the change in the value of the variable

measured on the horizontal axis by the change in the value of the variable

measured on the vertical axis.