Question

Jacob finds a correlation of .55 between scores on a newly developed questionnaire to measure determination to succeed and grades at Tarrant County College (TCC).

12) Based on this correlation, we can explain or predict how much of the variability in grades at TCC by students’ determination to succeed score? What two other factors might account for the unexplained the variance in student grades?

Answer 1

Correlation = 0.55

Percent of variation explained by the succed score in grade is can be found by using the coefficient of determination is R squared.

R squared = (correlation)^2

=0.55*0.55

=0.3025

Therefore 30.25% of the  variability in grades at TCC by students’ determination to succeed score.

Unexplained variance = 1-0.3025 = 0.6975

69.75 percent of unexplained  variability in grades at TCC by students’ determination to succeed score.

The factor we cann add is number of hours of study & grades in midterm exam.or IQ score of the students to decrease unexplained variability