The long median time to graduation at California State University, Northridge (CSUN) is five years and fewer than fifty percent of first time freshmen graduate in less than eight years. We have used data mining and predictive analytics to determine some of the key academic indicators of success at CSUN. The most important indicators that we have found are (a) first math course attempted; (b) grade point average (GPA) at the end of each of the first two terms; and (c) successful completion of a freshman experience seminar course (UNIV 100). When all three are considered simultaneously, we can correctly identify over two thirds of the students who will drop out without graduating, while incorrectly misidentifying approximately one-fifth of students who ultimately graduate as at-risk of not graduating.
One of the tools we use is logistic regression.
The Achievement Gap
An achievement gap is a disparity in educational measures between the performance of students in different groups. Such gaps have been most frequently noted between different racial, economic, and gender groups.
At CSUN the achievement can be seen in the following logistic regression, which predicts the probability of graduating in six years based on GPA at the end of the first semester. It was based on aggregated data from students who started as freshmen at CSUN in 2005, 2006, and 2007 (and hence would have graduated by 2011, 2012, or 2013, respectively).
Pell grants are provided by the government based on income to students; approximately one third of all students in the US receive Pell grants. The maximum award for 2015-2016 is $5775 per year, but for many students is less. Since most students who are eligible for Pell grants apply and receive some aid, we expected that a students’ Pell grant status would approximately reflect their socio-economic status. However, a student’s Pell grant status is not a significant predictor of graduation, as the following would seem to suggest:
Does Living on Campus Help?*
Whether or not students live on campus dos not, at first appearance, look like a good predictor of the gap:
However, the above plot combines all students together. What this plot shows is that living on campus, in and of itself, is not specifically an predictor of success for all ethnic and socio-economic groups.
As the following plot shows, when the data is broken down by group, we see that African American students who live on campus have a significantly higher likelihood of graduation than similar African American students with the same GPA who do not live on campus.
This is in start contrast to other groups. For example, non-hispanic white students who live on campus actually have a lower chance of graduating, than other students with comparable GPA’s at the end of their first semester. In fact, the higher performing students tended to do worse on campus.
Lower-performing Asian-American students who live on campus have a slightly higher probability of graduation compared to other students with the same GPA at the end of their first semester. There is less improvement for higher-performing Asian-Americans.
The results are particularly perplexing for Latino students. The graduation rate is better for lower achievement students when they live on campus, and is better for higher achievement students when they live off campus.
*Plots prepared by Jorge Martinez and Andrew Miller