Quantifying the Impact of Absences in the Context of Covid, a Q&A with Monica Lee

April 20, 2021

We sat down with Dr. Monica Lee, co-author of The Short- and Long-Run Impacts of Secondary School Absences and Reducing Student Absenteeism in the Early Grades by Targeting Parental Beliefs, to contextualize the potential impact of missed learning time during Covid. 


In your paper, you examine student absences and achievement. What is the goal of your research?

We wanted to quantify the extent to which absences harm achievement in the secondary school setting. Much of the existing research in the past has looked at the correlation between absenteeism and achievement. A good amount of the research also focuses on whole-day absences, whereas we know that middle and high school students experience absenteeism in more nuanced ways. The research team wanted to nail down a cause and effect relationship between absenteeism and student outcomes. We were uniquely positioned to do this because of the data we were able to access. Specifically, we wanted to look at both short and long-term effects of absenteeism on student outcomes. 

What was the impact of absenteeism on achievement?

What we found was that missing 10 English Language Arts (ELA) classes resulted in a reduction of 3-4%of a standard deviation for ELA standardized test scores, and 17-18% of a standard deviation in end of course grades. There was a similar effect for missing math classes on math test scores and course grades. This is equivalent to the effect of replacing an average-quality teacher with a teacher from the 20th percentile of the effectiveness distribution. 

The magnitude of the effect of absences on achievement is greater than the one we see in educational interventions, such as reducing class size from 22 to 15 students. What this means is that improving attendance is a strategic and low-cost approach to improving achievement. 

So, how is it possible to determine that absences are responsible for student achievement? Couldn’t other external factors—like bullying or student sickness—be impacting student performance as well?

The analysis "differences out" the type of effect that something like bullying or illness might have on students' performance and engagement, successfully allowing us to isolate the relationship between absences and achievement alone. The data that we used was key; we could reliably look at secondary school students' absences for every day of the year in every course they were enrolled in, across over a decade. So our statistical modeling allows us to minimize the potential bias that external factors can have on absences as well as  achievement by looking individually at ELA outcomes and math outcomes for a specific student and corresponding absences in each subject. Though the evidence is not as strong as a randomized experiment, it’s pretty close and the best evidence to date when using administrative data to gauge the relationship between attendance and achievement in middle and high schools. 

Were there any surprising findings? Were any absences “more important” than others?

Absences are harmful for everyone, at all times, across all subjects. However, we found that mid- to late-spring absences were particularly harmful to student achievement, more so than absences earlier on in the year. This is likely because it is harder to recover from loss of instructional time when students miss school later in the school year. Aside from this difference in timing of absences, the relationship between absences and student outcomes is surprisingly similar across all student background and school contexts.

You mentioned there were longer-term impacts of absenteeism, too. Could you talk about that?

When our team looked at ninth grade student data, we found that every 10 absences reduces the probability of an on-time graduation and college enrollment by 2%. During the decade for which we studied the data, only 70% of students graduated high school on time, so this impact is more significant than it might seem at first glance. 

What implications does this research have in the context of unfinished learning in the times of and widening educational inequities?

Let’s assume that the average student missed 60 days of school in the spring of 2020 and that little to no learning occurred during these very early days of implementing distance education in half of those days (or 30 days). In this scenario, the resulting effect of missing in-person schooling on student outcomes is about 0.12 SD. Missing 30 days during the early onset of the pandemic would also decrease the likelihood of high school graduation and college enrollment by 3–4%. 

Let’s also go on to assume that, some students participated in virtual learning for the entire duration of the school year 2020–2021, and that they were on their own for asynchronous learning for one day per week. In a hypothetical (but likely) scenario, some students would be experiencing little to no learning on that day, whether it’s due to lack of social supports, barriers to accessing learning material (like internet or device access), or something else. This means that students miss 25% of the school year, or 45 days of learning. Even in the best-case scenario, where students learn just as much in virtual learning as they do in in-person learning, these students who miss out on 45 days of learning face about 18% of a SD in unfinished learning as a result of their absenteeism.Furthermore, this can decrease the likelihood of graduation and college enrollment by up to 5-6%. 

Additionally, students of color, especially Black and Latinx students, face more systemic barriers to attendance. Before COVID-19, these students missed 2–3x the number of days as their White or Asian peers in the district we studied. If attendance programs and interventions could close the attendance gap between these groups, it would increase academic achievement among Black and Latinx students by 4-6% of a SD.


There is a real opportunity to reduce racial gaps in attendance and in achievement as part of an effort to increase equity in education. If educators consider creating environments that support student attendance through different programs and interventions, they can move the needle on other short- and long-run student outcomes, especially among student groups who are in greatest need of our support.


Dr. Monica Lee is a research adviser for EveryDay Labs. Formerly, she was a Research Fellow at the Student Social Support R&D Lab at Harvard Kennedy School. She earned her PhD in educational policy from Stanford University and her MEd in Education Policy and Management from the Harvard Graduate School of Education. She recently co-authored a working paper about absenteeism and student outcomes alongside Jing Liu (Brown University) and Seth Gershenson (American University).