Math Problem Statement

Refer to the accompanying scatterplota. Examine the pattern of all 10 points and subjectively determine whether there appears to be a strong correlation between x and y. b. Find the value of the correlation coefficient r and determine whether there is a linear correlationc. Remove the point with coordinates (9, 2) and find the correlation coefficient r and determine whether there is a linear correlationd. What do you conclude about the possible effect from a single pair of values? Click here to view a table of critical values for the correlation coefficient

Solution

To solve this problem, let us proceed step by step:

a. Subjective Examination of the Scatterplot

Look at the overall pattern of the 10 points in the scatterplot:

  • If the points follow a straight-line pattern closely, there is a strong correlation.
  • If the points are widely scattered or show no clear direction, there is weak or no correlation.

Based on your observation:

  • Is there a linear pattern?
  • Are there any outliers (like the point (9, 2)) that deviate significantly from the overall trend?

b. Calculate the Correlation Coefficient (r)

The formula for the correlation coefficient rr is: [ r = \frac{n \sum (x y) - \sum x \sum y}{\sqrt{[n \sum x^2 - (\sum x)^2][n \sum y^2 - (\sum y)^2]}} ] Where:

  • nn = number of points
  • x\sum x, y\sum y = sums of the xx and yy values
  • (xy)\sum (xy), x2\sum x^2, y2\sum y^2 = sums of products, squares of xx, and squares of yy

Once rr is calculated:

  • Compare r|r| with the critical value from the table of critical values for the correlation coefficient to determine if the correlation is significant.

c. Remove the Point (9, 2)

Recalculate rr without the point (9, 2) using the same formula as above.

  • Observe whether removing the point changes the correlation coefficient significantly.
  • Compare r|r| with the critical value again to assess the impact on significance.

d. Conclusion

Discuss the impact of removing the point (9, 2):

  • Does this single pair of values (9, 2) influence the correlation coefficient substantially?
  • What does this imply about the sensitivity of correlation to outliers?

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Math Problem Analysis

Mathematical Concepts

Statistics
Correlation and Regression Analysis
Linear Relationships

Formulas

Correlation coefficient formula: r = [nΣ(xy) - ΣxΣy] / √[(nΣx^2 - (Σx)^2)(nΣy^2 - (Σy)^2)]

Theorems

Concept of Linear Correlation
Effect of Outliers on Correlation

Suitable Grade Level

Grades 10-12