Connect with experts and get insightful answers to your questions on IDNLearn.com. Our platform is designed to provide reliable and thorough answers to all your questions, no matter the topic.

23. From the following table, calculate the coefficient of correlation by Karl Pearson's method:
[tex]\[
\begin{tabular}{|c|c|c|c|c|c|}
\hline $x$ & 6 & 1 & 10 & 4 & 8 \\
\hline $y$ & 9 & 11 & ? & 8 & 7 \\
\hline
\end{tabular}
\][/tex]

Ans:

(Note: Please ensure that the missing value for [tex]\( y \)[/tex] is provided to perform the calculation correctly.)


Sagot :

Sure, I'll walk you through the step-by-step process to calculate the Pearson correlation coefficient between the [tex]\(x\)[/tex] and [tex]\(y\)[/tex] variables, given the incomplete dataset and assuming that the missing value in [tex]\( y \)[/tex] can be imputed based on the remaining values.

### Step 1: Identify the missing value in [tex]\( y \)[/tex]
First, we need to impute the missing [tex]\( y \)[/tex] value using the available data in the [tex]\( y \)[/tex] column.

Given [tex]\( y = [9, 11, ?, 8, 7] \)[/tex], let's denote the missing value as [tex]\( y_3 \)[/tex].

We assume that the missing value in [tex]\( y \)[/tex] is equal to the mean of the rest of the [tex]\( y \)[/tex] values:
[tex]\[ \text{Mean of remaining } y = \frac{9 + 11 + 8 + 7}{4} = \frac{35}{4} = 8.75 \][/tex]

So, [tex]\( y_3 = 8.75 \)[/tex].

### Step 2: Complete the data
Now, we have the complete dataset:

[tex]\[ x = [6, 1, 10, 4, 8] \][/tex]
[tex]\[ y = [9, 11, 8.75, 8, 7] \][/tex]

### Step 3: Calculate the means of [tex]\( x \)[/tex] and [tex]\( y \)[/tex]

[tex]\[ \text{Mean of } x = \frac{6 + 1 + 10 + 4 + 8}{5} = \frac{29}{5} = 5.8 \][/tex]

[tex]\[ \text{Mean of } y = \frac{9 + 11 + 8.75 + 8 + 7}{5} = \frac{43.75}{5} = 8.75 \][/tex]

### Step 4: Calculate the covariance between [tex]\( x \)[/tex] and [tex]\( y \)[/tex]

[tex]\[ \text{Cov}(x, y) = \frac{1}{N} \sum_{i=1}^{N} \left( (x_i - \bar{x})(y_i - \bar{y}) \right) \][/tex]

[tex]\[ \text{Cov}(x, y) = \frac{1}{5} \left( (6 - 5.8)(9 - 8.75) + (1 - 5.8)(11 - 8.75) + (10 - 5.8)(8.75 - 8.75) + (4 - 5.8)(8 - 8.75) + (8 - 5.8)(7 - 8.75) \right) \][/tex]

[tex]\[ = \frac{1}{5} \left( 0.2 \times 0.25 + (-4.8) \times 2.25 + 4.2 \times 0 + (-1.8) \times -0.75 + 2.2 \times -1.75 \right) \][/tex]

[tex]\[ = \frac{1}{5} \left( 0.05 + (-10.8) + 0 + 1.35 + (-3.85) \right) \][/tex]

[tex]\[ = \frac{1}{5} \left( -13.25 \right) = -2.65 \][/tex]

### Step 5: Calculate the standard deviations of [tex]\( x \)[/tex] and [tex]\( y \)[/tex]

[tex]\[ \text{Std}(x) = \sqrt{ \frac{1}{N} \sum_{i=1}^{N} (x_i - \bar{x})^2 } \][/tex]

[tex]\[ \text{Std}(x) = \sqrt{ \frac{1}{5} \left( (6-5.8)^2 + (1-5.8)^2 + (10-5.8)^2 + (4-5.8)^2 + (8-5.8)^2 \right) } \][/tex]

[tex]\[ = \sqrt{ \frac{1}{5} \left( 0.04 + 23.04 + 17.64 + 3.24 + 4.84 \right) } \][/tex]

[tex]\[ = \sqrt{ \frac{48.8}{5} } = \sqrt{9.76} \approx 3.12 \][/tex]

[tex]\[ \text{Std}(y) = \sqrt{ \frac{1}{N} \sum_{i=1}^{N} (y_i - \bar{y})^2 } \][/tex]

[tex]\[ = \sqrt{ \frac{1}{5} \left( (9-8.75)^2 + (11-8.75)^2 + (8.75-8.75)^2 + (8-8.75)^2 + (7-8.75)^2 \right) } \][/tex]

[tex]\[ = \sqrt{ \frac{1}{5} \left( 0.0625 + 5.0625 + 0 + 0.5625 + 3.0625 \right) } \][/tex]

[tex]\[ = \sqrt{ \frac{8.75}{5} } = \sqrt{1.75} \approx 1.32 \][/tex]

### Step 6: Calculate the Pearson correlation coefficient

[tex]\[ r = \frac{\text{Cov}(x, y)}{\text{Std}(x) \times \text{Std}(y)} \][/tex]

[tex]\[ r = \frac{-2.65}{3.12 \times 1.32} \approx \frac{-2.65}{4.12} \approx -0.641 \][/tex]

### Summary
The Pearson correlation coefficient between [tex]\( x \)[/tex] and [tex]\( y \)[/tex] is approximately [tex]\( -0.641 \)[/tex]. Other intermediate results are:

- The imputed missing value in [tex]\( y \)[/tex] is [tex]\( 8.75 \)[/tex].
- The mean of [tex]\( x \)[/tex] is [tex]\( 5.8 \)[/tex].
- The mean of [tex]\( y \)[/tex] is [tex]\( 8.75 \)[/tex].
- The covariance between [tex]\( x \)[/tex] and [tex]\( y \)[/tex] is [tex]\( -2.65 \)[/tex].
- The standard deviation of [tex]\( x \)[/tex] is [tex]\( 3.12 \)[/tex].
- The standard deviation of [tex]\( y \)[/tex] is [tex]\( 1.32 \)[/tex].