1) Graphical Interpretation of Data (4 points)

a) For each correlation coefficient (r) given below, draw an appropriate trend line (if

possible) using fictitious X-Y data points.

10

8

6

4

2

19

0

0

X

Y

2

4

4.0

2.0

X

r> 0

8

7.0

4.0

10

10.0

10.0

10

8

0

0

2.0

3.5

6

5.0

9.0

X

r<0

8

20.0

10.0

10

14.0

5.0

10

8

2

b) Plot the following data set on arithmetic paper and draw a straight line through the data

points using eyeball-fitting method and find the equation of the line (do this manually).

Following that, estimate equation and the correlation coefficient of the least-square

regression for the data set using equations provided in the manual. Finally, plot the data set

using Excel and add a trendline together with its equation. Compare your equations with the

equation provided by excel. To what extent do you think these points can be represented by

a line?

0

11.0

10.0

4

14.0

14.5

X

6

r=0

8

16.0

17.0

10

6.0

21.0