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1. What are the three characteristics of a correlation? 2. What does a “positive

ID: 3155980 • Letter: 1

Question

1. What are the three characteristics of a correlation?

2. What does a “positive relationship” mean?

3. A Pearson correlation o fr=____________and r=_____________both indicate a perfect relationship.

4. The correlation between reading comprehension and problem solving skills is found to be r= +0.70. How much variability in problem solving skills can be accounted for by the relationship with reading comprehension?

5. What are the four common applications of the Pearson correlation?

6. Suppose that there is a correlation of r=+0.92 between test scores on math exams and test scores on physics exams. What does this mean? [For this item, you simply want to interpret the correlation coefficient, r, and describe the relationship between the variables based on r.]

7. Compute the Pearson correlation (r), and construct a scatter plot for the following set of data

X Y X2 Y2 XY

1 6

2 8

4 2

5 0

3 4

SPXY = _______________ SSX = _______________ SSY = _______________ Pearson r = _______________

The relationship between X and Y is (circle one): negative positive

The relationship between X and Y is (circle one): weak medium strong

The proportion of variability in X accounted for by Y = _______________

Explanation / Answer

1. What are the three characteristics of a correlation?

(a)

Correlation is symmetric between X and Y. That is correlation between X and Y is same as correlation between Y and X.

(b)

The value of correlation coefficient is lie between -1 and +1 (inclusive)

(c)

Correlation coeffcient do not have any unit. That is it is inependent from the units of variables.