Question

In the left column below are listed the r-values of various data sets, each of which contains 100 points. Descriptions of those data sets are shown in the right column. Match each r-value with the description of the data set with which it is most likely associated.

	r=0.1		A.	Data shows a clear upward trend
	r=0.6		B.	Data points lie quite close to a line with negative slope
	r=0.9		C.	Data shows a very slight upward trend
	r=−0.6		D.	Data shows a clear downward trend
	r=−0.9		E.	Data points lie quite close to a line with positive slope

Note: You can earn partial credit on this problem.

Answer 1

r-value is the correlation coefficient value between the two variables, it defines the strength of the relationship between the two variables.

Its value lies between -1 to 1, closer the value to -1 and 1 greater the strength of the relation ship. The sign of the value defines the type of the relationship if the value negative then the relationshib between the variables is inversly proportional and if the value is positive then the relation ship will be directly proportional to each other.

So, the correct matching of the statements are:

r=0.1	C.	Data shows a very slight upward trend
r=0.6	E.	Data points lie quite close to a line with positive slope
r=0.9	A.	Data shows a clear upward trend
r=−0.6	B.	Data points lie quite close to a line with negative slope
r=−0.9	D.	Data shows a clear downward trend