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2.5 Scatter Plots & Lines of Regression. Correlation. Scatter plots are data points: gathered, plotted and used to determine relationships. Line of Best Fit. The line that approximates the set of data. It’s essentially a line of average through the center of all the points
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Correlation • Scatter plots are data points: gathered, plotted and used to determine relationships
Line of Best Fit • The line that approximates the set of data. • It’s essentially a line of average through the center of all the points • Can be found by hand or using calculator • Line allows us to make future predictions
Scatter Plots and LoBF(by hand) • Find data, plot points • Sketch what you think LoBF is • Find two points on your line • Find slope • Use Point Slope Form and solve for y.
Example 1: Determine the line of best fit using the table of values given. Example 2: Use your LoBF to estimate the y-value when x is 12.
Scatter Plots & LoBF(w/ calculator) Line of Best Fit • STAT >> CALC • 4: LinReg (ax + b) - ENTER x2 Scatter Plots • Input Table -STAT >> EDIT - Data into L1 & L2 • Adjust Window - WINDOW • View Graph - 2nd >> Y = >> ENTER - Select “On” - GRAPH IF YOUR INPUTTED DATA IS NOT IN L1 & L2 SOME OF THIS WORK HAS TO CHANGE!
Graphing the Line of Best Fit Y= VARS 5: Statistics >> EQ >> ENTER 2nd >>> CALC >>> type in your value ENTER Predict using the Line of Best Fit
Example The table shows the winning times for an annual dirt bike race for the period 2000–2008.Use a graphing calculator to make a scatter plot of the data. Find and graph a line of regression. Then use the function to predict the winning time in 2015. Let t = 0 represent the year 2000.