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Chapter 9. Correlation & Linear Regression. Correlation. The relationship between two things ( x, y ) x is the independent (explanatory) variable y is the dependent (response) variable. Correlation & Scatterplots. Positive Correlation Negative Correlation Nonlinear Correlation
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Chapter 9 Correlation & Linear Regression
Correlation • The relationship between two things • (x, y) • x is the independent (explanatory) variable • y is the dependent (response) variable
Correlation & Scatterplots • Positive Correlation • Negative Correlation • Nonlinear Correlation • No Correlation
y x Positive Correlation
y x Negative Correlation
y x Nonlinear Correlation
y x No Correlation
y 10 10 8 6 4 2 x -10 -10 -8 -6 -4 -2 2 4 6 8 10 10 -2 -4 -6 -8 -10 -10 What is Linear Regression? What’s the equation of this line that best fits this data?
Perform a Linear Regression • Input Lists • x in L1 • y in L2 • 2nd #0 “Diagnostic On” • Stat • “Calculate Menu” • #4 “LinReg(ax+b)” • Enter r = -0.99
y 10 10 8 6 4 2 x -10 -10 -8 -6 -4 -2 2 4 6 8 10 10 -2 -4 -6 -8 -10 -10 Try Another One! • Perform a Linear Regression on the data. Find r. r = .95
y 10 10 8 6 4 2 x -10 -10 -8 -6 -4 -2 2 4 6 8 10 10 -2 -4 -6 -8 -10 -10 Try Another One! • Perform a Linear Regression on the data. Find r. r = -0.98
y 10 10 8 6 4 2 x -10 -10 -8 -6 -4 -2 2 4 6 8 10 10 -2 -4 -6 -8 -10 -10 Try Another One! • Perform a Linear Regression on the data. Find r. r = .94