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. 5 is an example of which of the following types of correlations?
a. cross-sectional correlation
b. autocorrelation
c. multivariate correlation
d. cross-lag correlation