In: Statistics and Probability
To test whether extracurricular activity is a good predictor of college success, a college administrator records whether students participated in extracurricular activities during high school and their subsequent college freshman GPA.
LEFT side of column: Activity RIGHT side: College GPA
(a). Code the dichotomous variable and then compute a point-biserial correlation coefficient. (Round your answer to three decimal places.)
Yes | 3.54 |
Yes | 3.28 |
Yes | 3.96 |
Yes | 3.71 |
No | 3.00 |
No | 3.82 |
No | 3.43 |
No | 2.79 |
No | 3.89 |
No | 2.75 |
The dichotomous variable Y = whether students participated in extracurricular activities during high school is coded as shown below,
Now, the point-biserial correlation coefficient is obtained in excel by following these steps,
Step 1: Write the data values in excel
Step 2: Calculate the standard deviation for variable X using the function =STDEV(). The screenshot is shot is shown below,
Step 3: Separate the X value in separate column for each Y value and calculate the mean. The screenshot is shot is shown below,
Step 3: The point-biserial correlation coefficient is obtained using the formula,