Question

a. Explain the meaning of the finding that there is a negative correlation between class attendance (number of absences) and achievement in class (as measured by the final examination). Use the concept of r square in your explanation.

b. A research article reports that there is 60% common association (or shared variance) between the scores on two measures. Explain what this means. How did they get the 60%? What was the correlation?

Answer 1

(a) if there is negative correlation between class attendance and achievement in class . then it implies that if class attendance is decreases then performance of class also decreases .

Let for above case r= -0.78 the R^2 = 0.60 this implies that about 60% of data shows that the if class attendance is less then class performance is weak .

(b) so here 60% variation is shared by the the scores it means R^2 =60 that 60% data explain the varriation of two scores . So R^2 is obtained by taking square of correlation coefficient r .

Here correlation coreficient is r = √0.60 = 0.774