The research, conducted by Claudia Finger, Sandra Hupka-Brunner and Andrés Gomensoro of the University of Bern, draws on the Swiss TREE study, short for Transitions from Education to Employment. TREE is one of the rare panel surveys in the world that tracks PISA participants over the long term. Its first cohort was launched in 2000, built on a nationally representative sample of Swiss ninth graders tested when the country joined PISA for the first time. The PISA survey achieved a remarkable 95 percent response rate, and roughly half of the initial TREE sample consented to follow-up contact, yielding a baseline of 6,343 respondents. Ten panel waves later, the most recent data cover almost twenty years and follow respondents from early adolescence to an average age of about 35.

This long observation window matters enormously, and it is precisely what most other PISA follow-up studies lack. Previous analyses in Luxembourg, Israel, Australia, Canada and Denmark have generally stopped observing participants in their early or mid-twenties. That cutoff creates two problems. First, more than a fifth of participants are still enrolled in tertiary education at that age, so the labor market outcomes of those already working are biased toward the less educated. Second, economists have shown that early-career earnings estimates suffer from a downward lifecycle bias, because people with higher lifetime earnings experience steeper wage growth. Returns to skills rise sharply until around age 35 and only then stabilize. By following respondents to 35, the Swiss team could capture outcomes far closer to their mature form.

The study’s central finding concerns educational attainment. Among the 2,887 respondents analyzed, 43 percent had obtained a tertiary degree by age 35, whether at a university, a university of applied sciences, or through a professional tertiary qualification. The researchers found that a 100-point increase in PISA reading scores, equivalent to one standard deviation on the international scale, raised the probability of earning a tertiary degree by almost 23 percentage points. Given that the sample average was already 43 percent, that is a substantial effect. Reading literacy, measured with Warm’s Weighted Likelihood Estimator and checked against plausible-value methods, proved to be the single strongest incremental predictor of degree attainment in the models, adding significant explanatory power beyond gender, migration background, parental occupational status and school track.

Perhaps the most technically interesting result involves the interaction between reading skills and Switzerland’s famously early tracking system. Swiss students are streamed into two to four lower-secondary tracks after grade six, at around age twelve, and although policy formally postulates permeability, initial placement is largely irreversible. Test-score distributions overlap substantially across tracks, yet the track itself acts as a powerful signal. The study shows that for students scoring below 500 points, the probability of later obtaining a tertiary degree differs little between tracks. But among higher-scoring students, track-specific differences widen dramatically: being in the lowest rather than the highest track significantly weakens the effect of strong reading skills. In other words, high literacy is especially helpful for students in the academic track, while it matters far less for those placed lower, because lower tracks do not commonly qualify for tertiary education despite formal permeability. Early tracking, the authors conclude, makes educational pathways path-dependent in ways that can neutralize individual skill advantages.

On the labor market, the picture is more nuanced. Neither PISA scores nor tertiary degrees were related to whether respondents were employed at all, which is unsurprising in a country where unemployment stood at just 4.4 percent in 2024 and the vocational education and training system integrates most school leavers into work. But among the 93.5 percent who were employed or self-employed, a 100-point increase in reading scores was associated with 8.5 percent higher gross hourly income, and with higher occupational prestige as measured by the International Socioeconomic Index. Crucially, the income association was fully mediated by tertiary degree attainment, while the occupational status association was reduced but remained visible after controlling for degrees. The direct effect on occupational status, however, was modest: three ISEI points amount to only a fifth of a standard deviation in prestige, corresponding to minor shifts between occupations. In a system with strong vocational specificity and powerful signaling value of certificates, educational credentials appear to be the main channel through which adolescent skills translate into labor market rewards.

The study also ventured beyond education and work into domains that PISA follow-ups rarely touch: health, wellbeing and political interest. Here the results were strikingly mixed. Self-assessed health, life satisfaction on a ten-point scale, and an additive index of positive life attitudes all showed no relationship to reading scores, and none to educational attainment or employment either. The authors offer several possible explanations. Self-rated health is a subjective measure that may capture different aspects than the objective health indicators used in earlier research linking skills to longevity and health service use. Health inequalities by education often widen over adulthood and may simply not have materialized by age 35. The TREE sample also excludes people who migrated to Switzerland after compulsory schooling, potentially underrepresenting more disadvantaged groups, and baseline health and life satisfaction in Switzerland are among the highest in the OECD, compressing the room for skill-based differences to appear.

One unexpected positive finding concerns democracy. Reading literacy at fifteen showed a modest but significant relationship with political interest at thirty-five, partly mediated by tertiary education. Intriguingly, the same analyses run with mathematics and science scores found no such link, suggesting that it is reading literacy specifically, rather than numeracy or scientific understanding, that feeds civic curiosity. In a country whose semi-direct democracy asks citizens to vote several times a year on federal, cantonal and local questions, that distinction carries real weight. It hints that the ability to comprehend complex texts may be a foundational civic skill, one that shapes engagement with political information long after the classroom test is forgotten.

The authors are careful about the limits of their evidence. Panel attrition is a constant concern in a twenty-year study, and the team used logistic-regression-based weights to correct for non-response, finding that participation in the final wave was predicted by prior participation patterns, education, nationality and, notably, PISA reading scores themselves. Between 15 and 17 percent of wave-ten respondents skipped the complementary questionnaire containing the health, wellbeing and political items, so the researchers tested whether adjusting for variables related to that non-response, such as life satisfaction, marriage and children, changed their conclusions; it did not. They also caution that respondents have completed less than half of their life course, that returns to skills may still be underestimated for those still establishing careers, and that health trajectories have decades left to unfold. An eleventh panel wave, fielded when respondents reached an average age of 40, will be released in 2027, with further waves planned at five-year intervals.

Beyond the Swiss case, the study speaks to a broader frustration in assessment research. PISA claims to measure the knowledge and skills needed in adult life, yet the evidence base for that claim has long been thin, and the handful of national follow-ups that exist are barely comparable, each built with different instruments, timelines and frameworks. An OECD report as far back as 2010 called for better coordination of longitudinal follow-ups, arguing that it would for the first time allow cross-national analysis of young people’s pathways from education into work. The Swiss findings, showing that adolescent reading literacy echoes through two decades of educational, economic and even civic life while leaving subjective wellbeing untouched, add a compelling piece to that cumulative puzzle, and a reminder that answering PISA’s central promise will require long-term commitment from funders, sustained panel data, and far more international coordination than currently exists.

Subject of Research: Long-term predictive validity of PISA reading literacy measured at age 15 for educational, labor market, health, wellbeing and political outcomes at age 35 in Switzerland

Article Title: Cognitive skills and long-term life outcomes: evidence from 19 years of PISA 2000 follow-up surveys in Switzerland

Article References: Cognitive skills and long-term life outcomes: evidence from 19 years of PISA 2000 follow-up surveys in Switzerland. (n.d.). https://doi.org/10.1186/s40536-026-00322-w

Image Credits: AI Generated

DOI: 10.1186/s40536-026-00322-w

Keywords: PISA, reading literacy, longitudinal study, TREE study, educational attainment, labor market outcomes, income, political interest, health, wellbeing, school tracking, Switzerland