PH 7B Public Health Statistics II
Homework 1
Question 1 (5 pts):
Which of the following correlation coefficients shows the
weakest
relationship?
A.
0.68
B.
-0.05
C. 0.50
D. -0.96
Explain:
The weakest relationship is -0.05 because the more a correlation is near to 0 the more
it shows the weaker relationship
Question 2 (5 pts):
True or False: If y is usually less than x, the correlation coefficient between
x and y will be negative.
True or False: False
Explain:
This is false because if x and y have a positive linear relationship the correlation
coefficient will be positive so it’s a possibility for y to be less than x and still have a positive r
value.
Question 3 (5 pts):
When exchanging x and y, the scatter plot will look ________, and the
correlation coefficient will be _______, and the slope of the regression line will be________.
A.
Different, the same, different
B.
Different, the same, the same
C. The same, different, the same
D. The same, the same, different
Explain:
The correlation coefficient indicates the direction of the relationship (positive or
negative), and will remain the same after swapping the variables.
