Identify what is wrong with each of the following statements: ...

[formula1]

Identify what is wrong with each of the following statements:
 
  a. The correlation between Olympic gold medal times for the 800m hurdles and year is -0.66 seconds per year.
 
  b. The correlation between Olympic gold medal times for the 100m dash and year is -1.37.
 
  c. Since the correlation between Olympic gold medal times for the 800m hurdles and 100m dash is -0. 41, the correlation between times for the 100m dash and the 800m hurdles is +0.41.
 
  d. If we were to measure Olympic gold medal times for the 800m hurdles in minutes instead of seconds, the correlation would be -0.66/60 = -0.011.

Question 2

After conducting a survey of his students, a professor reported that There appears to be a strong correlation between grade point average and whether or not a student works. Comment on this observation.
 
  What will be an ideal response?

[tjayeee]

Answer to Question 1

a. Correlation has no units.
b. Correlation has to be between -1 and +1.
c. Correlation does not change if we reverse the role of the x and y variables.
d. Correlation does not change when we change units.

Answer to Question 2

Correlation measures the strength of a linear association between two quantitative variables. Whether or not a student works is a categorical variable, so correlation cannot be calculated between GPA and whether or not a student works.