Question

A Statistics instructor has given the same pretest and the same final examination each semester for several (Number of students = 100) . He is interested in determining if there is a relationship between the scores of the two tests.

a. He computes the linear correlation coefficient and notes that r = .82 What does this correlation coefficient value tell the instructor ?

b. An Education instructor is also curious and conducts the same research using pretest and final results for his class of 14 students. In the case the instructor obtained an r = -1.07 What does this tell the instructor?

Answer 1

solution:

a.)Value of r

–1. A perfect negative linear relationship

–0.70. A strong negative linear relationship

–0.50. A moderate negative relationship

–0.30. A weak negative linear relationship

0. No linear relationship

+0.30. A weak positive linear relationship

+0.50. A moderate positive relationship

+0.70. A strong positive linear relationship

+1. A perfect positive linear relationship

ans:- as per above discussion we can conclude that  r = .82 means the relation between the variables is A strong positive linear relationship.

b.)

Ans:-Value of r is always between -1 to 1 , it can not be less than -1 and greater than +1. but if it happens this is due to multicollinearity

multicollinearity:-If two predictors are highly correlated or if one predictor has a large multiple correlation with the other predictors, there is said to be multicollinearity.