The pisa test scores ranking is one of the most closely watched benchmarks in global education, shaping policy decisions worth billions of dollars every three years. PISA — the Programme for International Student Assessment — is a pisa international test administered by the OECD to 15-year-olds in more than 80 countries and economies. Understanding where your country stands on the test pisa leaderboard matters not just to ministers and researchers, but to students, parents, and teachers who want to know how competitive their education system truly is on a global stage.
The pisa test scores ranking is one of the most closely watched benchmarks in global education, shaping policy decisions worth billions of dollars every three years. PISA — the Programme for International Student Assessment — is a pisa international test administered by the OECD to 15-year-olds in more than 80 countries and economies. Understanding where your country stands on the test pisa leaderboard matters not just to ministers and researchers, but to students, parents, and teachers who want to know how competitive their education system truly is on a global stage.
Each PISA cycle measures student performance across three core domains: reading literacy, mathematical literacy, and scientific literacy. Results are reported as scaled scores with a mean of approximately 500 points and a standard deviation of 100, allowing direct comparisons across borders. When the 2022 results were released, media headlines immediately focused on the pisa test scores by country, sparking national debates everywhere from Helsinki to Washington, D.C. The same happened again in September 2026, when the OECD published the PISA 2025 results — the PISA results 2026 by country covered below. The numbers carry genuine weight because they correlate strongly with long-term economic productivity and individual lifetime earnings.
For American students and educators, the pisa test results by country are both humbling and motivating. The United States has historically scored around the OECD average — sitting near the middle of the pack in mathematics while performing somewhat stronger in reading. In the 2022 assessment, the U.S. scored 465 in mathematics, 504 in reading, and 499 in science. These numbers represent a noticeable decline from 2018, partly attributed to COVID-19 learning disruptions, but they also reflect persistent structural challenges that predate the pandemic by decades.
The pisa test ranking is dominated year after year by a cluster of East Asian education systems. Singapore, China (specifically the four provinces of Beijing, Shanghai, Jiangsu, and Zhejiang, often abbreviated as B-S-J-Z), Japan, South Korea, and Taiwan consistently occupy the top positions. Their dominance is not accidental — it reflects deliberate investments in teacher quality, curriculum coherence, high expectations for all students regardless of socioeconomic background, and a cultural emphasis on academic achievement that permeates daily life from early childhood onward.
Examining pisa test scores across multiple cycles reveals important trends. Some countries have made dramatic improvements — Poland, for example, rose sharply between 2000 and 2012 by overhauling its school structure and delaying academic tracking. Others have experienced painful declines, most notably Finland, which was once the darling of international education reform but has seen its scores slip as economic inequality and immigration patterns have shifted its student demographics. These trajectories offer crucial lessons about which reforms actually work over time.
This comprehensive guide walks you through everything you need to know about the pisa test rankings: how scores are calculated, which countries lead and which are struggling, what drives performance differences, how the United States compares in detail, what the 2022 data revealed about the pandemic shock, and how the PISA scores by country 2026 release shows whether systems have recovered. Whether you are a student preparing for international assessments, an educator seeking context for your own classroom, or a curious citizen trying to understand global education trends, this article delivers the full picture backed by real data and expert analysis.
By the end of this guide you will also understand practical strategies for improving student performance — because understanding the pisa test country rankings is only valuable if it motivates concrete, evidence-based action in schools and homes. The OECD publishes enormous volumes of supplementary data alongside raw scores, and mining that data reveals which classroom practices, homework habits, and school funding models most reliably predict high achievement across diverse cultural and economic contexts.
Before looking at the newer PISA scores by country, it helps to know the baseline. The pisa test country rankings from the 2022 assessment delivered some of the most dramatic results in the program's history, largely because COVID-19 created unprecedented disruptions that affected some countries far more than others. Singapore reclaimed the undisputed top position in mathematics with a mean score of 575, a full 29 points ahead of second-place Macao (China) at 552.
Japan scored 536, Taiwan 547, and South Korea 527 — all comfortably above the OECD average of 472, which itself fell by the largest margin ever recorded between two consecutive cycles. The pandemic effectively erased two decades of cumulative PISA gains in mathematics in a single assessment period.
In reading literacy, Singapore again topped the global table with 543, followed by Ireland at 516, Japan at 516, and South Korea at 515. The reading domain showed somewhat less catastrophic pandemic-era decline than mathematics, partly because reading practice continued more naturally at home during lockdowns while structured mathematical instruction suffered more from school closures. Estonia — long regarded as Europe's highest-performing education system — maintained strong results with 511 in reading, cementing its reputation for equitable, high-quality schooling despite a modest national budget compared to wealthier Nordic neighbors.
Science literacy rankings placed Singapore at the top with 561, followed by Japan at 547, with South Korea at 528 and Estonia at 526 also near the top. Science scores were slightly more resilient than mathematics across most OECD nations, possibly because laboratory-based instruction, while disrupted, was supplemented more effectively by digital simulation tools. Canada scored 515 in science, Australia 507, and New Zealand 504 — all above the OECD average, reflecting well-resourced, English-speaking systems that maintained relatively more instructional continuity than many European peers during school closures.
Understanding what is pisa test scoring methodology is essential for interpreting these league tables correctly. PISA uses Item Response Theory (IRT) and plausible value methodology — no student answers every question. Instead, each student completes a subset of items, and sophisticated statistical models estimate their likely performance across the full item bank. This means raw scores cannot be compared to percentage-correct metrics; a score of 500 simply indicates average performance relative to the OECD baseline established in 2000, with each domain recalibrated periodically to maintain comparability.
Below the top performers, a fascinating middle tier reveals which countries are punching above their weight given economic constraints. Vietnam consistently outperforms expectations relative to its GDP per capita, scoring 469 in mathematics despite being a lower-middle-income country — higher than several wealthy European nations. Poland, the Czech Republic, and Slovenia cluster near or above the OECD average despite having education budgets far smaller than France, Sweden, or the United States. These outliers consistently teach researchers that spending alone does not determine outcomes; instructional quality, curriculum coherence, and teacher status matter enormously.
The bottom of the pisa test rankings reveals deep challenges. Among participating OECD members, Colombia, Mexico, and Chile consistently score well below average, though all three have shown improvement over multiple cycles. Among non-OECD participants, countries like Kosovo, the Dominican Republic, and Cambodia report scores below 350 in mathematics — more than two full standard deviations below Singapore. These gaps represent not just educational differences but profound disparities in economic opportunity, infrastructure, teacher training, and student nutrition that no single educational reform can bridge quickly.
Trend data across multiple PISA cycles is arguably more revealing than any single snapshot. Between 2000 and 2018, many countries showed genuine improvement — particularly in reading, where average scores across OECD nations rose meaningfully. Then came 2022, with its pandemic-driven collapse. The key question for the 2025 cycle was which countries would recover fastest — and the PISA scores 2026 publication answered it: for most OECD systems, they did not recover. Early evidence from national assessments suggests that countries that maintained more instructional time during 2020-2022 — through hybrid models, television broadcasts, or radio lessons in lower-resource settings — are rebounding most quickly, underscoring how foundational uninterrupted schooling really is.
The PISA ranking 2026 comes from the PISA 2025 assessment, whose results the OECD published on 8 September 2026. More than 760,000 students, representing about 33 million 15-year-olds in 91 countries and economies, took part, with science as the major domain. B-S-J-Z (China) posted the highest mean scores in science (597) and mathematics (612), while Singapore led reading with 535.
The headline of the 2026 release is decline. OECD averages were 482 in science, 461 in reading and 463 in mathematics, and between 2015 and 2025 OECD reading scores fell 28 points and mathematics 22 points. Science held up best. Small gaps between neighbouring countries are often not statistically significant, so read the table below as performance bands rather than exact places.
There is no separate PISA test 2026 sitting: the 2026 scores come from students tested in 2025, and the next cycle, PISA 2029, makes reading the focal domain again.
| Science rank | Country / economy | Science | Reading | Mathematics |
|---|---|---|---|---|
| 1 | B-S-J-Z (China) | 597 | 527 | 612 |
| 2 | Singapore | 560 | 535 | 563 |
| 3 | Macao (China) | 541 | 501 | 549 |
| 4 | Chinese Taipei | 540 | 508 | 546 |
| 5 | Japan | 538 | 503 | 525 |
| 6 | Estonia | 527 | 499 | 508 |
| 7 | Korea | 526 | 501 | 522 |
| 8 | United Kingdom | 511 | 494 | 488 |
| 9 | Canada* | 510 | 490 | 485 |
| 10 | Australia | 509 | 491 | 478 |
| — | United States* | 502 | 490 | 463 |
| — | OECD average | 482 | 461 | 463 |
Source: OECD, PISA 2025 Results (Volume I), Table I.1. * Caution required: one or more PISA sampling standards were not met. Australia and New Zealand both scored 509 in science.
East Asian education systems dominate the pisa test scores ranking cycle after cycle. Singapore, Japan, South Korea, Taiwan, and China's four benchmark provinces consistently occupy the top five slots in mathematics and science. These systems share several structural features: highly competitive university entrance processes that motivate intensive study from early adolescence, strong cultural norms around academic effort, and career ladders that reward teacher expertise with genuine social prestige and competitive salaries relative to national averages.
The mathematics gap between East Asia and the OECD average widened dramatically in 2022 — Singapore's 575 sat 103 points above the OECD mean of 472. Critically, these top performers also show relatively low variance between their highest and lowest socioeconomic quartiles, meaning their systems do a better job than most of lifting disadvantaged students toward high performance. Japan's variance is particularly low, reflecting a nationally uniform curriculum and strong school funding equity across rich and poor districts.
European PISA results in 2022 revealed a stark north-south and east-west divide. Estonia led the continent in all three domains, achieving remarkable equity alongside quality — its gap between highest and lowest socioeconomic quartiles is among the smallest on the continent. Finland, once ranked first globally, now sits near the middle of European scores, a decline attributed to rising immigration, relaxed homework culture, and fragmentation of the core curriculum through excessive school choice reforms introduced in the 2010s.
Southern European nations — particularly Greece, Italy, and Spain — continue to score 15-30 points below the OECD average in mathematics, though all three have shown modest improvement trends since 2006. Eastern European standouts like Poland and the Czech Republic outperform wealthier western neighbors like France, where persistent socioeconomic segregation between elite and ordinary schools creates wide achievement gaps. Germany's results improved meaningfully between 2000 and 2012 after its initial shocking underperformance triggered national education reform, but COVID set back progress sharply in 2022.
Within the Americas, Canada remains the clear regional leader, consistently scoring above the OECD average in all three domains despite enormous geographic diversity and a large immigrant student population. Canada's strength lies in provincial funding equity, strong teacher training programs, and a commitment to multilingual education that appears to benefit rather than hinder literacy development. The United States clusters around the OECD average in reading and science but falls below in mathematics — a gap that has persisted across nearly every PISA cycle since 2000.
Australia and New Zealand lead the Oceania region, both scoring above OECD averages in science and reading, though both saw significant declines in mathematics in 2022. Latin American nations — Brazil, Mexico, Colombia, Argentina, and Peru — all score well below OECD averages, though Brazil and Peru have shown improvement trends over multiple cycles. These countries face systemic challenges including high teacher turnover, underfunded rural schools, and high rates of grade repetition that research consistently shows is counterproductive to long-term learning outcomes in any national context.
| Pros | Cons |
|---|---|
| Provides genuinely comparable cross-national data using rigorous psychometric methodology | Tested domains (math, reading, science) exclude arts, civic education, physical health, and social-emotional learning |
| Tracks trends over time, revealing whether reforms are working across full policy cycles | High-stakes media coverage creates pressure for teaching-to-the-test rather than genuine learning |
| Covers equity as well as average performance, showing gaps between rich and poor students | Sampling challenges in large, diverse nations like China mean results may not represent entire populations |
| Motivates national policy debate and education investment in underperforming systems | Three-year cycles mean results are already outdated by the time policy responses are implemented |
| Includes context questionnaires linking scores to school resources, teacher quality, and family factors | Cannot account fully for cultural differences in test-taking motivation that may inflate or deflate scores |
The single most predictive metric in PISA data is not average score but socioeconomic gradient — the degree to which family wealth predicts student performance. Countries like Estonia, Canada, and Japan show low gradients, meaning disadvantaged students perform much closer to wealthy peers than in France, the U.S., or Germany. Systems that break this link between poverty and performance at age 15 tend to sustain high average scores across decades, while systems with steep gradients eventually plateau or decline as inequality compounds across generations.
What actually drives high PISA test scores ranking performance? Decades of PISA data, supplemented by OECD thematic reports and independent academic research, point consistently to five interconnected factors: teacher quality and status, curriculum coherence and rigor, instructional time used effectively, low socioeconomic variance in school funding, and a school culture of high expectations for all students regardless of background. No single factor alone explains the East Asian advantage or the Estonian miracle — it is always the combination working in mutually reinforcing ways.
Teacher quality is perhaps the most frequently cited driver. Countries like Finland and Singapore recruit teachers exclusively from the top third of university graduates, invest heavily in pre-service training, provide structured mentoring in the first three years of practice, and offer career pathways that reward pedagogical expertise rather than administrative advancement. Singapore's National Institute of Education runs one of the world's most rigorous teacher preparation programs, combining deep subject-matter knowledge with evidence-based instructional techniques and regular classroom observation cycles throughout a teacher's career.
Curriculum coherence means that what is taught in each grade builds logically on what came before, without the repetitive re-teaching of topics that plagues fragmented systems. The U.S., for example, historically suffered from what reformers called a "mile wide, inch deep" curriculum — covering enormous numbers of topics superficially rather than developing deep understanding of fewer concepts. High-performing PISA nations typically use nationally aligned curricula with clear learning progressions, ensuring that a student who moves between schools or regions encounters consistent instruction rather than chaotic coverage gaps or redundancies.
Instructional time matters, but the quality of that time matters more than raw quantity. Research consistently shows that time spent in active, cognitively demanding tasks — solving novel problems, discussing reasoning, writing extended arguments — predicts PISA scores far better than time spent in passive listening or rote memorization. South Korean students spend enormous hours studying, but the structured intensity of their study — with deliberate practice, immediate feedback, and progressive difficulty — is what converts time into performance. Simply adding school hours without improving what happens in them produces little measurable gain.
Funding equity is a structural prerequisite that high performers take seriously. In Finland, Estonia, and Japan, school funding is distributed roughly equally across rich and poor districts, sometimes with additional resources directed to schools serving disadvantaged populations. The United States, by contrast, funds schools heavily through local property taxes, creating dramatic funding disparities between wealthy suburban districts and impoverished urban or rural ones. PISA data consistently shows that countries with more equitable resource distribution achieve both higher average scores and smaller gaps between their top and bottom performers simultaneously — the classic high-quality-high-equity combination.
School climate and student motivation complete the picture. PISA questionnaires reveal that students in top-performing systems report stronger sense of belonging, less bullying, more constructive teacher-student relationships, and clearer understanding of why academic effort matters for their futures. South Korean and Japanese students report high levels of academic anxiety alongside high performance — a complex mix that raises questions about wellbeing — while Estonian and Canadian students combine high performance with relatively positive school experience. The OECD actively tracks student wellbeing alongside academic outcomes, recognizing that sustainable high performance cannot be built on chronic student stress alone.
Growth mindset research, associated with psychologist Carol Dweck, finds strong echoes in PISA data. Students who believe intelligence is malleable — that effort and good strategy improve their abilities — consistently outperform peers with fixed mindsets even after controlling for socioeconomic background and prior achievement. Top-performing PISA nations embed growth mindset messaging into teacher training and classroom culture, ensuring students understand that the struggle of learning a difficult concept is not a signal of inadequacy but the actual mechanism through which the brain builds capability. This belief, reinforced daily by instructional practice, transforms how students respond to academic challenge.
The United States' performance on the pisa international test has been a source of ongoing national debate since PISA's first administration in 2000. American policymakers initially dismissed the results, arguing that the U.S. serves a uniquely diverse and immigrant-heavy population that makes comparison to more homogeneous countries unfair.
Over time, however, that argument lost force as research showed that even when controlling for student demographics, U.S. performance remains mediocre in mathematics and average in reading — well short of what the nation's education investment would predict. Total per-pupil spending in the U.S. is among the highest in the OECD, making its middling outcomes particularly troubling.
The 2022 U.S. results told a particularly sobering story. American 15-year-olds scored 465 in mathematics — 7 points below the already depressed OECD average of 472 — down from 478 in 2018. Reading scores fell to 504 from 505, and science dropped to 499 from 502. In the PISA rankings 2026 (PISA 2025 data), the U.S. scored 463 in mathematics, 490 in reading and 502 in science, with the OECD advising particular caution because sampling standards were not met.
While the absolute declines look modest in isolation, they confirm that the U.S. did not recover from pandemic disruptions any better than the average OECD nation despite spending enormously on pandemic educational relief. The American Rescue Plan directed approximately $190 billion to K-12 education recovery — more than most OECD nations spent per capita — yet the test results suggest the money did not translate into measurable learning recovery by 2022.
Equity gaps within the United States are particularly stark. PISA data breaks scores down by socioeconomic quartile, and the U.S. shows one of the steeper gradients among OECD nations — meaning family wealth predicts student scores more strongly in America than in most comparable wealthy countries.
The gap between the highest and lowest socioeconomic quartiles in U.S. mathematics performance exceeds 100 PISA points — roughly the equivalent of three full years of schooling. Closing even half of that gap would lift average U.S. scores above the OECD mean and dramatically improve the life trajectories of millions of students currently left behind by systemic under-investment in high-poverty schools.
Individual U.S. states show dramatically different performance levels. Massachusetts, which has consistently outperformed the national average on NAEP (the National Assessment of Educational Progress — America's domestic equivalent of PISA), would rank among the top 10 countries globally if it participated as an independent entity. Minnesota and New Jersey also show strong performance. Meanwhile, Mississippi, West Virginia, and New Mexico score well below the national average domestically, reflecting the profound impact of poverty, rural isolation, and historically underfunded school systems on student outcomes. PISA's national aggregate conceals this massive internal variation.
Improvement pathways for the U.S. are well-documented even if politically difficult to implement. Research consistently points to three high-use interventions: raising teacher preparation standards and compensation to attract stronger candidates into the profession, adopting a coherent national mathematics curriculum with proven effectiveness rather than the current patchwork of state standards, and dramatically expanding high-quality early childhood education to close readiness gaps before children enter kindergarten.
Countries like Estonia and Canada demonstrate that none of these reforms requires authoritarian centralization — they can be implemented within democratic, decentralized education systems through smart incentive design and sustained political will across multiple election cycles.
Interested readers should explore the what is a pisa test resource to understand precisely how PISA items are structured and what cognitive demands they place on students. American students who encounter genuine PISA mathematics items often find them genuinely challenging — not because they require advanced mathematical knowledge, but because they require flexible application of mathematical reasoning to unfamiliar real-world contexts rather than the procedural calculation drills that dominate many U.S. mathematics classrooms.
This mismatch between what American schools teach and what PISA rewards is itself a major finding, suggesting that curriculum reform rather than more testing is the most direct path to score improvement.
Longitudinal analysis across all eight PISA cycles from 2000 to 2022 shows that the U.S. has essentially flatlined in mathematics while other nations have improved. The same OECD data shows that the achievement gap between the U.S. and top-performing Asian nations has widened, not narrowed, over the past two decades.
This is not destiny — Poland's dramatic turnaround and Estonia's sustained excellence prove that meaningful improvement is possible within a single generation when the right reforms are implemented with consistency and adequate resources. The question for American education is whether the political system can sustain reform long enough to see the results that only emerge over 10 to 15 years of patient implementation.
If your goal is to perform at the highest possible level on PISA-style assessments — or on the domestic tests, college entrance exams, and international benchmarks that mirror PISA's approach — practical preparation strategies make a measurable difference. The first and most important step is understanding that PISA tests applied reasoning, not memorized facts. Every question presents a real-world scenario and asks students to use literacy or numeracy to analyze, interpret, or evaluate something. Students who approach preparation by practicing this applied reasoning mindset rather than drilling formulas or vocabulary lists consistently outperform those who rely on rote study.
For mathematics specifically, the single highest-use practice activity is solving novel word problems that require setting up a mathematical model before calculating anything. PISA mathematics consistently penalizes students who can execute algorithms but cannot identify which algorithm applies to an unfamiliar situation.
Working through problems from released PISA item banks — freely available on the OECD website and on practice platforms like PracticeTestGeeks — trains the pattern-recognition and mathematical modeling skills that pure textbook practice rarely develops. Spending 20 to 30 minutes per day on this type of applied problem-solving for eight to twelve weeks produces measurable improvements in performance on PISA-style assessments.
Reading preparation should focus on three specific sub-skills that PISA emphasizes: locating and retrieving information from complex texts, integrating information across multiple documents or sources, and evaluating the quality and credibility of information. The last skill has become increasingly important as PISA has added more digital reading tasks requiring students to navigate websites, evaluate source reliability, and synthesize information across hyperlinked content. Students who regularly read news articles, scientific reports, and opinion pieces — and who practice actively questioning source credibility — develop these skills naturally, but targeted practice with actual PISA reading items accelerates development significantly.
Science preparation benefits enormously from focusing on scientific inquiry methodology rather than biological or chemical content knowledge. PISA science does not primarily test whether students know the names of organelles or the steps of the Krebs cycle. Instead, it tests whether students can design a fair experiment, interpret graphical data, identify confounding variables, and evaluate competing scientific explanations for a phenomenon.
These skills transfer across all science content areas and can be practiced with simple everyday scenarios — analyzing a newspaper report on a medical study, evaluating the methodology of a psychology experiment, or designing a test to determine which of two materials is more water-resistant.
Time management during PISA testing matters more than most students realize. Because items are administered via computer in most recent cycles, and because response times are tracked (though not always scored), developing habits of working efficiently without rushing is essential. Students who spend too long on difficult items and fail to reach later, potentially easier items consistently underperform relative to their actual ability level.
Practice under timed conditions using complete PISA sample test sessions — not individual items — trains the pacing skills needed to maximize score within the allotted time. The OECD publishes complete sample tests online, and platforms like PracticeTestGeeks offer structured timed practice with performance analytics.
Understanding the pisa test ranking proficiency levels is a powerful motivational tool for students who want to set concrete improvement goals.
PISA reports results on six proficiency levels ranging from Level 1 (basic tasks) through Level 6 (highly sophisticated reasoning). Knowing which level you currently perform at — and understanding precisely what cognitive tasks characterize the next level up — gives study sessions a clear, actionable target rather than a vague aspiration to "do better." The OECD's published level descriptors specify exactly what a Level 4 student can do in mathematics that a Level 3 student cannot, making self-assessment and targeted practice genuinely possible.
Finally, wellbeing and mindset cannot be separated from performance preparation. PISA's own research shows that students who report high test anxiety — disproportionately common in highly competitive East Asian systems despite those systems' strong average results — perform significantly below their capacity during assessments.
Developing pre-assessment routines that manage stress, practicing relaxation techniques, maintaining healthy sleep schedules in the days before testing, and approaching the assessment with a genuine sense of curiosity rather than fear all contribute meaningfully to peak performance. These are not soft extras — they are evidence-based performance interventions supported by PISA's own psychometric data across dozens of countries and hundreds of thousands of students assessed over more than two decades.
Try these questions from our free PISA - Program for International Student Assessment practice tests. The correct answer and an explanation follow each question.
A PISA report shows that the performance gap in reading between students in the top and bottom quarters of the PISA index of economic, social, and cultural status (ESCS) is 95 points in Country X. Which of the following is the most accurate interpretation of this finding?
Answer: A. Socio-economic background is strongly associated with student performance in Country X.
The PISA index of economic, social, and cultural status (ESCS) is a composite measure used to capture students' family and home background. A large point difference between students at the top and bottom of this index indicates a strong relationship between socio-economic background and academic performance, suggesting significant equity challenges within the education system.
An analyst observes that Country A has a mean mathematics score of 510 and Country B has a mean score of 500. To determine if Country A's performance is genuinely higher, what is the most critical piece of information the analyst must consider?
Answer: A. The standard error of the mean for each country.
PISA results are estimates based on a sample of students. To determine if the difference between two mean scores is 'real' and not just due to random sampling variation, one must conduct a test of statistical significance. The standard error is essential for this test, as it measures the uncertainty around the mean score. A small difference in means may not be statistically significant if the standard errors are large.
A high school has been selected to participate in PISA. The principal appoints a teacher to manage all logistical aspects of the assessment, including preparing student lists, scheduling the test sessions, and acting as the main point of contact for the PISA National Center. What is the official PISA title for this crucial administrative role?
Answer: C. School Coordinator
The School Coordinator is the designated individual within a participating school responsible for liaising with the PISA National Center and overseeing all administrative and logistical tasks required for the successful implementation of the PISA assessment at the school level.
Country Y's mean science score was 490 in PISA 2018 and 505 in PISA 2022. Country Z's mean science score was 510 in 2018 and 515 in 2022. Based only on this information, which conclusion is invalid without further statistical analysis?
Answer: A. Country Y showed more significant improvement than Country Z.
While Country Y has a larger point increase (15 points vs. 5 points), we cannot conclude its improvement is more 'significant' in a statistical sense without considering the standard errors for the scores in both years for both countries. A larger point change might not be statistically significant if the uncertainty around the estimates is high, while a smaller change could be.
Take the full PISA - Program for International Student Assessment practice test