Retention in the PTC is measured in three ways:

Enrollment by semester includes 21 variables measuring whether or not a student was enrolled at a CUNY institution up to 10 years from entry. These variables take the form enrolled_semxx where the xx is a two-digit number ranging from 01 to 21. These.variables either have a value of 0 or 1, zero indicating the the student was not enrolled in that semester and 1 indicating that the student was enrolled. Note that this variable does not distinguish between students who are not enrolled because they have already completed their degree and those who are not enrolled prior to completing a degree.

System retention variables measure retention outcomes regardless of where the student is in the system.Institutional retention variables measure retention conditional on the student's outcome being at the same institution as their home institution.

The system retention variables are measured on a fall-to-fall (and spring-to-spring for spring entrants) basis. That is, ret01 measures a student's retention one year from their semester of entry (e.g. if a student entered in fall 1999, then ret01 measures their status in fall 2000). The system retention variables go out 10 years from the semester of entry (i.e. ret10 is measured in the 21st semester). These variables can take five values:
Code
Meaning
1
Still Enrolled
2
Awarded Certificate
3
Awarded Associate Degree
4
Awarded Bachelor's Degree
5
Other (i.e. not enrolled pre-degree)

The institution retention variables are calculated in the PTC extract (the system retention variables are already in the IRDB). Like the system retention variables they are measured on a fall-to-fall and spring-to-spring basis. Unlike the system variables, they only take two values: 0 or 1. A value of 0 indicates that a student was not retained (either enrolled or earned a degree) in the relevant semester and a 1 indicates that they were either still enrolled at their entry college or had earned a degree from that college.