You generate a scatter plot using Excel. You then have Excel plot the trend line and report the equation and the r2 value. The regression equation is reported as y = 96.35z + 77.69 and the r2 = 0.36. What is the correlation coefficient for this data set?

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### Linear Regression and Correlation Coefficient

When performing a linear regression analysis, you typically generate a scatter plot using software like Excel. The next step is to plot the trend line and find the corresponding regression equation and \( r^2 \) value.

In this example, Excel reports the regression equation as:

\[ y = 96.35x + 77.69 \]

Additionally, it provides the \( r^2 \) value:

\[ r^2 = 0.36 \]

To understand the strength and direction of the linear relationship between the variables, we need to calculate the correlation coefficient, denoted as \( r \).

**Question: What is the correlation coefficient for this data set?**

You can calculate the correlation coefficient by taking the square root of \( r^2 \). Since \( r^2 = 0.36 \), we compute \( r \) as follows:

\[ r = \sqrt{0.36} \]

Since \( r \) can be either positive or negative depending on the direction of the relationship:

\[ r = \pm 0.6 \]

So, the correlation coefficient for this data set can be \( +0.6 \) or \( -0.6 \), indicating a moderate positive or negative linear relationship, respectively. The actual sign of \( r \) would depend on the nature of the data and the slope of the regression line. Given that the slope of the regression equation \( 96.35 \) is positive, \( r \) would be \( +0.6 \).
Transcribed Image Text:### Linear Regression and Correlation Coefficient When performing a linear regression analysis, you typically generate a scatter plot using software like Excel. The next step is to plot the trend line and find the corresponding regression equation and \( r^2 \) value. In this example, Excel reports the regression equation as: \[ y = 96.35x + 77.69 \] Additionally, it provides the \( r^2 \) value: \[ r^2 = 0.36 \] To understand the strength and direction of the linear relationship between the variables, we need to calculate the correlation coefficient, denoted as \( r \). **Question: What is the correlation coefficient for this data set?** You can calculate the correlation coefficient by taking the square root of \( r^2 \). Since \( r^2 = 0.36 \), we compute \( r \) as follows: \[ r = \sqrt{0.36} \] Since \( r \) can be either positive or negative depending on the direction of the relationship: \[ r = \pm 0.6 \] So, the correlation coefficient for this data set can be \( +0.6 \) or \( -0.6 \), indicating a moderate positive or negative linear relationship, respectively. The actual sign of \( r \) would depend on the nature of the data and the slope of the regression line. Given that the slope of the regression equation \( 96.35 \) is positive, \( r \) would be \( +0.6 \).
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