PSYC Statistical homework

PSYC 2317 Mark W. Tengler, M.S.

Assignment #4

Correlation

4.1 What information is provided by the sign (+ or -) of the Pearson correlation?

4.2 What information is provided by the numerical value of the Pearson correlation?

4.3 For the following set of data:

X Y 1 0 2 2 4 6 5 8 3 4

a. Sketch a graph showing the location of the five X,Y points. b. Just looking at your graph, estimate the value of the Pearson correlation. c. Compute the Pearson correlation for this data set using the formula sheet

handed out in class.

4.4 It is well known that similarity in attitudes, beliefs, and interests plays an important role in interpersonal attraction (see Byrne, 1971, for example). Thus, correlations for attitudes between married couples should be strong. Suppose a researcher developed a questionnaire that measures how liberal or conservative one’s attitudes are. Low scores indicate that the person has liberal attitudes, whereas high scores indicate conservatism. The following hypothetical data are scores for married couples.

Couple Wife Husband A 11 14 B 6 7 C 18 15 D 4 7 E 1 3 F 10 9 G 5 9 H 3 3

PSYC 2317 Mark W. Tengler, M.S.

Compute the Pearson correlation for these data (previous page), and determine:

a. whether or not there is a relationship between attitudes for husbands and wives (yes or no). Explain your answer.

b. what type of relationship there is, if any (positive or negative). Explain your answer.

c. how strong or weak the relationship is, if any. How do you know?