Linear Regression Line & Correlation Coefficient (day 2)
Key Concept
Correlation Coefficient “r”
“r” is a value tells whether the correlation is positive, negative, and how closely the equation models the data.
r = 1 r = 0 r = -1
Strong No Strong
Positive Correlation Negative
r = 0.98 Positive r = -0.99
Strong Strong
Positive Negative
r = 0.50 r = -0.49
Weak Weak
Positive Negative
How do we find the equation of linear regression using graphing calculator?
Stat - edit - 1 - enter all data on L1 and L2 - stat - calc - 4 - enter (5 times)
1. Walking Q
Choose the scatter plot which could possibly have the given r-value:
r = 0.50 A B C D E F
r = -0.89 A B C D E F
r = 0.92 A B C D E F
r = -0.85 A B C D E F
r = -1 A B C D E F
r = -0.48 A B C D E F
2. Jogging Q
Which value of r represents data with a strong negative linear correlation between two variables?
-1.07
-0.89
-0.14 4) 0.92
3.
Which value of r represents data with a strong positive linear correlation between two variables?
0.89
0.34
1.04
0.01
4. What could be the approximate value of the correlation coefficient for the accompanying scatter plot?
-0.85
-0.16
0.21
0.90
5. The points in the scatter plot below represent the ages of automobiles and their values. Based on this scatter plot, it would be reasonable to conclude:
Age and value have a coefficient of correlation that is less than zero.
Age and value have a coefficient of correlation that is equal to zero.
Age and value have a coefficient of correlation that is between zero and 0.5.
Age and value have a coefficient of correlation that is greater than 0.5.
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