DS280 - Intro to Statistics

Lecture Review #23 - Correlation

REVIEW QUESTIONS:

1) What is a covariance? How is it computed?

2) What does a correlation measure? How is it computed?

3) What is meant by a correlation of +1? Of -1? Of 0?

4) What is meant by a positive correlation? A negative correlation? Give examples of each, to illustrate.

COMPUTATIONAL EXERCISES:

1) Find the correlation for the following data:

2) The Admissions Office at the University of Southern North Dakota at Hoople is studying how well the data on a high school student's application to the university predict eventual success in college. The table below, from an unrealistically small sample of five students, gives data on their high school grade point average as well as their g.p.a. after the first year in college. Find the correlation between these two variables.

SOLUTIONS:
1) .8      2) .537