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Question
Math
Posted 8 months ago

The scatterplot below displays a set of bivariate data along with its leastsquares regression line.

Consider removing the point (66,15)(66,15) and calculating a new least-squares regression line.

What effect(s) would removing this point have?
Choose all answers that apply:

A The coefficient of determination (r2)\left(r^{2}\right) would decrease.
B The standard deviation of the residuals would decrease.
C The correlation coefficient (r)(r) would get closer to -1 .
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Answer from Sia
Posted 8 months ago
Solution by Steps
step 1
Identify the outlier in the scatterplot
step 2
Recognize that the point (66,15) lies above the regression line and is an outlier
step 3
Understand that removing an outlier can affect the regression line, the correlation coefficient, and other statistical measures
step 4
Predict that removing the outlier will likely result in a regression line that better fits the remaining data points
step 5
Anticipate that the correlation coefficient rr will likely increase in absolute value, getting closer to -1 if the outlier is in the direction of the positive correlation
step 6
Expect that the standard deviation of the residuals will decrease because the outlier that is contributing to a larger spread of residuals is removed
step 7
Consider that the coefficient of determination r2r^2 will likely increase, reflecting a better fit of the regression line to the data points without the outlier
Answer
B The standard deviation of the residuals would decrease. C The correlation coefficient (r)(r) would get closer to -1.
Key Concept
Impact of Removing an Outlier on Regression Analysis
Explanation
Removing an outlier from a set of data points can lead to a decrease in the standard deviation of the residuals and an increase in the absolute value of the correlation coefficient, reflecting a stronger linear relationship between the variables.

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