statistics

1. Which of the following correlation coefficients represents the strongest relationship?

a) r = .80
b) r = .20
c) r = -.45
d) r = -.85

2. The correlation coefficient for two variables, X and Y, is r = 60. Which of the following is true.
a) People who score high on x tend to score low on y
b) People who score high on x tend to score high on y
c) People who score low on x tend to score high on y

3. What type of correlation (positive or negative) would likely be obtained from the following sets of variables?
+ – Reaction time and driving skill
+ – Years of education and income
+ – Math anxiety and statistics achievement
+ – Years of experience and beginning salary

4. Suppose that the correlation between height and weight is .80, while the correlation between weight and caloric intake is .40. Indicate which of the following statements are true and which are false.
There is an 80% relationship between height and weight
True False
The correlation between height and weight is twice as strong as r = .40
True False
64% of the variability in weight can be accounted for by height
True False
An increase in one’s height causes a corresponding increase in weight
True False

5. Define Internal Validity (including the various threats) and provide a brief example for each threat.