22+Scatter+Plots+and+Best+Fit+Lines

Section 5-7 Scatter plots and Best Fit Lines

**Scatter plots** are similar to line graphs in that they use horizontal and vertical axes to plot data points. Scatter Plot : a graph in which two sets of data are plotted as ordered pairs in a coordinate plane

**Correlation** : a relationship between two events Positive Correlation : as X increases, Y increases Negative Correlation : as X increases, Y decreases No Correlation : If the plot does not appear to rise or fall then there is no correlation

Here are examples of some specific **Scatter Plots**:





**Line of Best Fit** : a straight line that best represents the data on a scatter plot
Here is an example of a Best Fit Line on a scatter plot: It is important to remember that NO one line will pass through all of the data points. The line will be drawn so that it passes close to the points.

A __Line of Best Fit__ is used to make predictions.

To solve for a Line of Best Fit we need to use slope-intercept form: **y=mx+b** //y coordinate= slope(x coordinate)+ y-intercep//t But first if we are given two sets of ordered pairs, we need to find the slope by using the equation **m=__Y2-Y1__ X2-X1**

Example 1) This is an example where we are given two sets of ordered pairs, which means that we first need to find the slope of the ordered pairs then plug the numbers into y=mx+b. After you plug in the slope, and the x and y coordinates, solve the problem. After solving for //b// plug in the slope and the y-intercept (//b//) into **y=mx+b** to form an equation.

Example 2) Example 3) This is an example where we are given only one ordered pair, but we are already given the slope of the line. All we need to do is plug in! After you plug in the ordered pair and the slope, solve for //b//. After finding the value of //b//, plug in the slope and the y-intercept into the equation **y=mx+b** to form your final equation.

Helpful Links:
[|Make Your Own Scatter Plot] [|Scatter Plot Practice Problems] [|Learn How to Make a Scatter Plot in Excel] [|*Line of Best Fit examples] (provides a clear, step by step procedure on how to draw a line of best fit, and how to solve the equation) [|Scatter Plot Quiz]