Researchers were interested in assessing whether high school GPA is associated with graduating from college in 4 years. At graduation, a group of 5,000 college students were assessed to determine who completed their degree in 4 years compared to those who completed their degree in more than 4 years. In total, 2800 students completed their degree in 4 years. At the same time, students were asked about their high school GPA. Of the students surveyed, 1,500 had a GPA < 3.0 in high school, of whom 600 graduated in 4 years. What type of study was conducted