Math Problem Statement
Use a calculator to verify that Σx = 24.2, Σx2 = 86.12, Σy = 53.5, Σy2 = 459.33 and Σxy = 190.28. Compute r. (Round your answer to four decimal places.)
Solution
To compute the correlation coefficient , we use the formula:
[ r = \frac{n \sum xy - (\sum x)(\sum y)}{\sqrt{[n \sum x^2 - (\sum x)^2][n \sum y^2 - (\sum y)^2]}} ]
Where:
- is the number of data points
- is the sum of the -values
- is the sum of the squares of the -values
- is the sum of the -values
- is the sum of the squares of the -values
- is the sum of the products of and
Given values:
Step-by-Step Calculation:
- We first need the value of . From the sums, we can estimate as the number of pairs of data points. Since , , etc., seem to be sums over data pairs, let’s assume (since we have sums for both and , and typically such problems use small sample sizes).
- Now, substitute the values into the formula:
[ r = \frac{5 \times 190.28 - (24.2)(53.5)}{\sqrt{[5 \times 86.12 - (24.2)^2][5 \times 459.33 - (53.5)^2]}} ]
Let's calculate each component:
Numerator:
Denominator:
First, calculate each square term and then the products: Now substitute into the denominator:
Final Calculation:
Now, we can compute :
So the correlation coefficient .
Since the value of should lie between and , it appears that either the data provided is not consistent with the usual range for a correlation coefficient, or there might be a mistake with the given sums. You may want to verify the sums.
Would you like further clarification or details on this? Or do you have other questions?
Here are 5 related questions:
- How can we interpret the value of the correlation coefficient?
- How do changes in the data affect the correlation coefficient?
- What are the conditions for calculating correlation?
- What are the implications of an -value that is outside the typical range?
- How can the formula for be applied to real-world data?
Tip: Always double-check the data inputs when performing calculations like correlation to ensure accuracy.
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Math Problem Analysis
Mathematical Concepts
Statistics
Correlation Coefficient
Summation Notation
Formulas
r = (n Σxy - (Σx)(Σy)) / √[(n Σx2 - (Σx)^2)(n Σy2 - (Σy)^2)]
Theorems
Pearson Correlation Coefficient Formula
Suitable Grade Level
Grades 11-12
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