Dr. Farah is an educational psychologist who is interested in studying the potential causal relationship between doing homework and academic achievement. In January, Dr. Farah has her students report their fall GPA (a measure of academic achievement) and estimate how many hours they spent doing homework during a typical week in the fall semester. In May, Dr. Farah measures the same variables again (the estimated number of hours spent doing homework during a typical week in the spring semester and their spring GPA). She finds the following correlations.
Variable A Variable B Correlation
Coefficient
Correlation 1 Fall number of Fall semester GPA .83*
hours of homework
Correlation 2 Fall number of Spring number of .36*
hours of homework hours of homework

Correlation 3 Fall number of Spring semester GPA .69*
hours of homework

Correlation 4 Fall semester GPA Spring number of .18
hours of homework
Correlation 5 Fall semester GPA Spring semester GPA .45*
Correlation 6 Spring number of
hours of homework Spring semester GPA .80*
* Indicates a statistically significant relationship.
Which of the correlations is an autocorrelation?
A. Correlation 1
B. Correlation 2
C. Correlation 4
D. Correlation 6