Math Problem Statement

Find the correlation coefficient for the data displayed in the table below: x: {1, 3, 5, 7, 9, 11, 13}, y: {3, 8, 11, 12, 16, 21, 28}.

Solution

To calculate the correlation coefficient for the given data, we will use the formula for the Pearson correlation coefficient:

r=nxyxy(nx2(x)2)(ny2(y)2)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:

  • nn is the number of data points,
  • xx and yy are the individual data points,
  • x\sum x, y\sum y, x2\sum x^2, and y2\sum y^2 are the sums of xx, yy, squares of xx, and squares of yy, respectively,
  • xy\sum xy is the sum of the products of corresponding xx and yy values.

Let's start by calculating the necessary values step-by-step from the provided table:

xyx×yx \times yx2x^2y2y^2
13319
3824964
5115525121
7128449144
91614481256
1121231121441
1328364169784

Now, we compute the sums:

  • x=1+3+5+7+9+11+13=49\sum x = 1 + 3 + 5 + 7 + 9 + 11 + 13 = 49
  • y=3+8+11+12+16+21+28=99\sum y = 3 + 8 + 11 + 12 + 16 + 21 + 28 = 99
  • xy=3+24+55+84+144+231+364=905\sum xy = 3 + 24 + 55 + 84 + 144 + 231 + 364 = 905
  • x2=1+9+25+49+81+121+169=455\sum x^2 = 1 + 9 + 25 + 49 + 81 + 121 + 169 = 455
  • y2=9+64+121+144+256+441+784=1819\sum y^2 = 9 + 64 + 121 + 144 + 256 + 441 + 784 = 1819

We can now substitute these values into the Pearson correlation formula:

r=7×90549×99(7×455492)(7×1819992)r = \frac{7 \times 905 - 49 \times 99}{\sqrt{(7 \times 455 - 49^2)(7 \times 1819 - 99^2)}}

Let's compute this step-by-step: math

Values from the table

n = 7 sum_x = 49 sum_y = 99 sum_xy = 905 sum_x_squared = 455 sum_y_squared = 1819

Calculate the correlation coefficient using the formula

numerator = n * sum_xy - sum_x * sum_y denominator = math.sqrt((n * sum_x_squared - sum_x ** 2) * (n * sum_y_squared - sum_y ** 2))

Pearson correlation coefficient

r = numerator / denominator rThe Pearson correlation coefficient for the given data is approximately 0.979. This indicates a very strong positive linear relationship between the variables xx and yy.

Would you like further details or clarification on any part of the calculation?

Here are 5 related questions that could help expand on this topic:

  1. How can you interpret the value of the correlation coefficient in terms of the strength and direction of the relationship?
  2. What other methods can be used to assess the linear relationship between two variables?
  3. How does the correlation coefficient relate to the regression line in a scatter plot?
  4. What are the limitations of using the Pearson correlation coefficient for data analysis?
  5. How can you perform a hypothesis test for the correlation coefficient?

Tip: The correlation coefficient is sensitive to outliers. A small number of extreme values can heavily influence its value, so it's always useful to visualize the data (using a scatter plot) to check for such outliers before making conclusions.

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Math Problem Analysis

Mathematical Concepts

Statistics
Correlation Coefficient
Linear Relationship

Formulas

Pearson Correlation Coefficient Formula: r = (nΣxy - ΣxΣy) / sqrt((nΣx² - (Σx)²) * (nΣy² - (Σy)²))

Theorems

Properties of the Correlation Coefficient

Suitable Grade Level

Grades 10-12