The impact of attendance has long been a key question in education, particularly its effects on the learning and broader development of young people. This includes - but is not limited to - headline measures of school and student performance, such as GCSE grades and Progress 8 scores.
But accurately quantifying the effect of absence on such student outcomes is not an easy task. This is because there is the problem of what researchers call “confounding” from other variables.
For instance, we know that students with lower levels of prior achievement and those from disadvantaged socioeconomic backgrounds are more likely to be absent from school. They also tend to achieve lower marks in assessments.
The raw relationship between student absence and future measures of academic achievement will hence partly pick up the impact of these background factors, rather than the effect of higher rates of student absence per se.
Researchers have used a variety of approaches to try and get around this problem. This includes investigating differences in absence rates across siblings and how this relates to differences in later academic achievement.
Others have exploited random variation induced by “chance” events - such as snow days - that force some students to miss a day (or several days) of school.
UCL Institute of Education’s Centre for Equalising Opportunity and Education Policy published a useful summary of the evidence on this matter a couple of years ago. It suggests that, for every three days a student misses school, their test scores will decline by an “effect size” of 0.01 standard deviations.
Or, to put this into plain English, if a student misses eight days of school, our best guess from the existing evidence is that they will fall one place in a ranking of 100 students (from 50th to 51st position, for example).
Cumulative effects
This may not seem to be a big deal: effect sizes of this magnitude look pretty small. But the impact of school absence may accumulate over time. So, if we instead think about the impact of persistent absence over the entirety of a student’s time at school, this may result in a substantial amount of learning loss.
Consider three hypothetical children, who we will follow from the start of Reception through to the end of Year 11.
Child A has a 100 per cent record of attendance over their 12 years at school, while Child B consistently meets the “persistent absent” threshold (10 per cent of sessions missed) and the absence rate for Child C is even higher, at 15 per cent per year.
Each academic year is 190 days long, which means that Child B will attend school for almost 230 fewer days in total than Child A. Based on the best evidence currently available, this translates into Child B slipping 28 positions in our ranking of 100 children relative to Child A.
The comparison between Child A and Child C is even starker. The former would be present at school for around 340 more days in total than the latter. This translates into a difference of 37 places in the ranking of 100 students.
Although this thought experiment is relatively crude, it nevertheless helps to illustrate how a student who continually meets the definition of persistent absence may really suffer in terms of their achievement.
It is important to recognise, however, that there are a series of issues that this simple thought experiment has not considered. These may moderate the aforementioned results - either for better or for worse. Evidence from Belgium, for example, suggests that absences at certain points in the academic year (most notably the start and end of school terms) may be more detrimental to learning than others.
The relationship between absence and achievement may also be non-linear. For instance, perhaps missing a couple of days of school each year has virtually no impact on student outcomes.
But - for each additional day over, say, a week - the negative effect could become ever-larger. To my knowledge, we currently know little about such issues, and whether there is a certain level of absence above which the detrimental effect of each additional day is particularly large.
Unequal absences
Perhaps most importantly, though, is that the impact of school absence will to some extent depend on what young people are doing instead.
Take someone who is struggling with their mental health. They therefore decide they do not want to go to school on a particular day - but are highly motivated to cover the material they are missing while they are at home. In such a situation, the amount of learning lost may be relatively small.
In contrast, another young person may simply decide to play Fortnite all day with their friends. Clearly, not much learning will be going on, and the learning lost will be much greater. Absences from school come in many shapes and sizes, and their respective impacts will not be equal.
But we don’t currently have enough high-quality evidence on how prolonged periods of persistent absence may impact broader aspects of young people’s development.
One may, for instance, broadly draw an analogy between young people being persistently absent from school and long-term unemployment among adults. For the latter, we have good evidence that sustained periods without a job can lead to a deterioration in working-age adults’ wellbeing and in “soft” skills such as conscientiousness.
The existing academic evidence points towards the academic impacts of persistent absence being bad, it could be that the social and emotional consequences for young people could be even worse.
Arguably parents, teachers and the wider education sector should be focusing on tackling the root causes of such disengagement in school among young people, rather than narrowly focusing on absence per se. After all, getting a young person to attend school - but without simultaneously boosting how engaged they are in their studies - may only solve a small part of what is a much bigger problem.
John Jerrim is professor of education and social statistics at University College London
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