Lesson #14 Assignment
1. 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.

2. 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
______________________________

Compute the Pearson correlation for these data, and determine whether or not there is a 
significant correlation between attitudes for husbands and wives. Set alpha at .05, two tails.

3. Assuming a two-tailed test with α = .05, how large a correlation is needed to be statistically
significant for each of the following samples?
a. A sample of n = 15 individuals
b. A sample of n = 30 individuals
c. A sample of n = 92 individuals

4. A psychologist would like to determine whether there is any consistent relationship
between intelligence and creativity. A random sample of n = 18 people is obtained and the
psychologist administers a standardized IQ test and creativity test to each individual. Using
these data, the psychologist obtains a Pearson correlation of r = +0.20 between IQ and
creativity. 
a. Do the sample data provide sufficient evidence to conclude that a real (nonzero) 
correlation exists in the population? Test at the .05 level of significance.
b. If the same correlation, r = 0.20, was obtained for a sample of n = 102 people, what
decision would be made about the population correlation?

5. For the following set of data,
___________
__X____Y__
1 2
4 7
3 5
2 1 
5 14
3 7
__________

a. Compute the Pearson correlation.
b. Find the linear regression equation for predicting Y from X.
c. Use the regression equation to compute the predicted Y for each value of X.