2.6 Draw Scatter Plots and Best-Fitting Lines

Scatter Plot A scatter plot is a graph used to help determine whether there is a relationship between paired data. Sometimes scatter plots follow patterns that are approximately linear.

Scatter Plot In the scatter plot shown, y tends to increase as x increases. Positive Correlation We say the paired data has a positive correlation with a correlation coefficient of r=1.

Scatter Plot In the scatter plot shown, y tends to decrease as x increases. Negative Correlation We say the paired data has a negative correlation with a correlation coefficient of r=-1.

Scatter Plot No Correlation No Linear Pattern?? We say the paired data has a Relatively no correlation with a correlation coefficient of r=0.

Approximating Best-Fitting Lines for a Scatter Plot Sketch a line that appears to the pattern of the line. (9,6) There should be as many points above the line are there are below the line. (-1,-4) Pick two points on the line, and estimate the coordinates of each. These two points do not have to be original data points. Use the point-slope formula to find the equation of the line. y = x-3 This equation models the data