Researchers have long been interested in quantifying how inputs like school quality and years of education translate into personal earnings over time and individual contributions to the larger economy. The common consensus is that more school leads to more human capital, as demonstrated by higher wages for those with more formal education than their peers. A recent meta-study aggregates dozens of research reports on the topic and finds reason to question this prevailing belief.
An international trio of economics researchers focuses specifically on studies that exploit administrative changes—such as a change in the minimum school-leaving age for a state or country or labor law revisions that raise the minimum age that children can legally work—to identify causal relationships between individuals with more/less schooling and their later life earnings. They find 79 independent estimates of these types of relationships from 53 separate papers published around the world. The various studies involved data collected from 1945 into the 21st century, mainly in Western democracies, and affecting students between 10 and 16 years of age.
Overall, the combined findings mirror the common consensus, averaging an 8.2 percent boost in individual income for an additional year of education. But this robust return masks several rigorous studies that actually found null effects. The researchers also provide evidence that there are “missing” findings that have gone unpublished which would serve to reduce the impacts of more education even further. The authors argue that if there is a “true positive effect” of education—whatever percentage boost that may be—the findings of numerous studies on this effect, when mapped all together, should resemble a bell curve clustering around the “true number.” Some papers will show larger impacts, some smaller, and maybe even some negative results, but the distribution should be close to a normal one. However, these 79 sets of findings form a curve that is accurate at the top end but becomes irregular as it approaches zero and drops off sharply below zero.
The researchers’ analysis indicates that studies showing null or negative effects of increased time in school rarely see the light of day, and they attribute this fact to two forms of publication bias: a greater likelihood of a report being published when it is statistically significantly positive, as well as authors building or tweaking methodologies in order to get positive results which will be published.[1]
After correcting for both of these types of bias—essentially, constructing a normal distribution by filling in the missing portions of the curve—the authors conclude that the real effect of an additional year of schooling on individual earnings is likely somewhere in the 0 to 3 percent range. Much lower than the published research consensus. The report does not delve into reasons why additional time in school might not lead to higher earnings, but it may have to do with higher-quality studies that typically control for academic ability, given that kids who are better at school would likely be the ones staying in school longer.
In their conclusion, the report’s authors focus most strongly on the implications for economics research, noting that evidence of publication bias in favor of positive results is not new, and that its ongoing existence is a drag on the field’s integrity. But for education researchers and reformers, the likelihood that the economic return for an additional year of schooling is small to nothing should be the headline.
Manhattan Institute Fellow Robert VerBruggen, for example, writes in a recent Substack post that he sees three implications from these findings. First, indiscriminately pushing all kids to get the maximum amount of K–12 education possible does not seem to be a supportable policy position. Second, although pushing kids to the maximum amount isn’t the answer, the impacts of more school don’t go negative even after correcting for publication bias, so it follows that the amount of education students are receiving is probably just about right. Third, the point at which any given student has “enough” education to max out their future earnings—especially in relation to the postsecondary college vs. career debate—is still unknown and should be the focus of future analysis.
SOURCE: Gregory Clark, Christian Alexander, and Abildgaard Nielsen, “The Returns to Education: A Meta-Study,” Kyklos, the International Review for Social Sciences (February 2026).
[1] The authors did not uncover a drawer full of unpublished papers with null findings—that type of bias is implied—but they did observe use of many “weak instruments” in the published papers engineered to ignore or minimize null findings as “outliers”.
