Scatter Plots
A scatter plot is used when the data for all variables are numerical and continuous. Each piece of data is represented by a point. (See Example 1)

In a line graph, each data point in the scatter plot is connected to the next point in the data set with a straight line. (See Example 2)

Two or more data sets can be plotted on the same graph to show relationships to the same independent variable. If the second data set has differing dependent variable or units, it may be plotted on the right vertical axis. (See Example 3)

In some scatter plots, a straight or curved line is drawn through the entire data set to show the general trend in data. A straight line that mathematically best fits the data is called a regression line. (See Example 4)

Alternatively, a mathematical function that best fits the data may describe a curved line, called a best-fit curve. (See Example 5)