4.2.2 Scatter Plots and Trend Lines Key Objectives • Graph scatter plots from data. • Describe correlations of scatter plots.
• Identify correlations of data sets. • Match scatter plots to situations. • Draw trend lines to make predictions. Key Terms
• A scatter plot is a graph with points plotted to show a possible relationship between two sets of data. • A correlation is a description of a relationship between two data sets. A correlation can help analyze trends and make predictions. • Two data sets have a positive correlation when their data values increase or decrease together. • Two data sets have a negative correlation when one set of data values increases while the other decreases. • Two data sets have no correlation when there is no relationship between their data values. • A trend line is a line on a scatter plot that helps show the correlation between data sets more clearly. Example 1 Graphing a Scatter Plot from Given Data To make a scatter plot from a given data set, write each pair of data values as an ordered pair and then graph each ordered pair. The points are usually scattered on a coordinate plane.
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