To test whether extracurricular activity is a good predictor of college success,
ID: 3360156 • Letter: T
Question
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.
(a) Code the dichotomous variable and then compute a point-biserial correlation coefficient. (Round your answer to three decimal places.)
Activity College
Freshman GPA Yes 3.49 Yes 3.31 Yes 3.93 Yes 3.72 No 2.92 No 3.81 No 3.39 No 2.77 No 3.92 No 2.84
Explanation / Answer
Result:
x
y
1
3.49
1
3.31
1
3.93
1
3.72
0
2.92
0
3.81
0
3.39
0
2.77
0
3.92
0
2.84
point-biserial correlation r = ((m1-m0)/s)*sqrt(p*q)
m1=3.6125
m2=3.275
s=0.4445
p=0.4, q=0.6
r = ((3.6125-3.275)/0.4445)*sqrt(0.4*0.6)
=0.37197
=0.372 ( three decimals).
x
y
1
3.49
1
3.31
1
3.93
1
3.72
0
2.92
0
3.81
0
3.39
0
2.77
0
3.92
0
2.84
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