NCES Blog

National Center for Education Statistics

U.S. Is Unique in Score Gap Widening in Mathematics and Science at Both Grades 4 and 8: Prepandemic Evidence from TIMSS

Tracking differences between the performance of high- and low-performing students is one way of monitoring equity in education. These differences are referred to as achievement gaps or “score gaps,” and they may widen or narrow over time.

To provide the most up-to-date international data on this topic, NCES recently released Changes Between 2011 and 2019 in Achievement Gaps Between High- and Low-Performing Students in Mathematics and Science: International Results From TIMSS. This interactive web-based Stats in Brief uses data from the Trends in International Mathematics and Science Study (TIMSS) to explore changes between 2011 and 2019 in the score gaps between students at the 90th percentile (high performing) and the 10th percentile (low performing). The study—which examines data from 47 countries at grade 4, 36 countries at grade 8, and 29 countries at both grades—provides an important picture of prepandemic trends.

This Stats in Brief also provides new analyses of the patterns in score gap changes over the last decade. The focus on patterns sheds light on which part of the achievement distribution may be driving change, which is important for developing appropriate policy responses. 


Did score gaps change in the United States and other countries between 2011 and 2019?

In the United States, score gap changes consistently widened between 2011 and 2019 (figure 1). In fact, the United States was the only country (of 29) where the score gap between high- and low-performing students widened in both mathematics and science at both grade 4 and grade 8.


Figure 1. Changes in scores gaps between high- and low-performing U.S. students between 2011 and 2019

Horizontal bar chart showing changes in scores gaps between high- and low-performing U.S. students between 2011 and 2019

* p < .05. Change in score gap is significant at the .05 level of statistical significance.

SOURCE: Stephens, M., Erberber, E., Tsokodayi, Y., and Fonseca, F. (2022). Changes Between 2011 and 2019 in Achievement Gaps Between High- and Low-Performing Students in Mathematics and Science: International Results From TIMSS (NCES 2022-041). U.S. Department of Education. Washington, DC: National Center for Education Statistics, Institute of Education Sciences. Available at https://nces.ed.gov/pubsearch/pubsinfo.asp?pubid=2022041.


For any given grade and subject combination, no more than a quarter of participating countries had a score gap that widened, and no more than a third had a score gap that narrowed—further highlighting the uniqueness of the U.S. results.


Did score gaps change because of high-performing students, low-performing students, or both?

At grade 4, score gaps widened in the United States between 2011 and 2019 due to decreases in low-performing students’ scores, while high-performing students’ scores did not measurably change (figure 2). This was true for both mathematics and science and for most of the countries where score gaps also widened.


Figure 2. Changes in scores of high- and low-performing U.S. students between 2011 and 2019

Horizontal bar chart showing changes in scores of high- and low-performing U.S. students between 2011 and 2019 and changes in the corresponding score gaps

p < .05. 2019 score gap is significantly different from 2011 score gap.

SOURCE: Stephens, M., Erberber, E., Tsokodayi, Y., and Fonseca, F. (2022). Changes Between 2011 and 2019 in Achievement Gaps Between High- and Low-Performing Students in Mathematics and Science: International Results From TIMSS (NCES 2022-041). U.S. Department of Education. Washington, DC: National Center for Education Statistics, Institute of Education Sciences. Available at https://nces.ed.gov/pubsearch/pubsinfo.asp?pubid=2022041.


Low-performing U.S. students’ scores also dropped in both subjects at grade 8, but at this grade, they were accompanied by rises in high-performing students’ scores. This pattern—where the two ends of the distribution move in opposite directions—led to the United States’ relatively large changes in score gaps. Among the other countries with widening score gaps at grade 8, this pattern of divergence was not common in mathematics but was more common in science.

In contrast, in countries where the score gaps narrowed, low-performing students’ scores generally increased. In some cases, the scores of both low- and high-performing students increased, but the scores of low-performing students increased more.

Countries with narrowing score gaps typically also saw their average scores rise between 2011 and 2019, demonstrating improvements in both equity and achievement. This was almost never the case in countries where the scores of low-performing students dropped, highlighting the global importance of not letting this group of students fall behind.  


What else can we learn from this TIMSS Stats in Brief?

In addition to providing summary results (described above), this interactive Stats in Brief allows users to select a subject and grade to explore each of the study questions further (exhibit 1). Within each selection, users can choose either a more streamlined or a more expanded view of the cross-country figures and walk through the findings step-by-step while key parts of the figures are highlighted.


Exhibit 1. Preview of the Stats in Brief’s Features

Image of the TIMSS Stats in Brief web report


Explore NCES’ new interactive TIMSS Stats in Brief to learn more about how score gaps between high- and low-performing students have changed over time across countries.

Be sure to follow NCES on TwitterFacebookLinkedIn, and YouTube and subscribe to the NCES News Flash to stay up-to-date on TIMSS data releases and resources.

 

By Maria Stephens and Ebru Erberber, AIR; and Lydia Malley, NCES

Program for the International Assessment of Adult Competencies (PIAAC) 2022–23 Data Collection Begins

Last month, the National Center for Education Statistics (NCES) kicked off a major survey of adults (ages 16–74) across the nation to learn about their literacy skills, education, and work experience. Information collected through this survey—officially known as Cycle 2 of the Program for the International Assessment of Adult Competencies (PIAAC) in the United States—is used by local, state, and national organizations, government entities, and researchers to learn about adult skills at the state and local levels (explore these data in the PIAAC Skills Map, shown below).


Image of PIAAC Skills Map on state and county indicators of adult literacy and numeracy


Specifically, these data are used to support educational and training initiatives organized by local and state programs. For example, the Houston Mayor’s Office for Adult Literacy has used the PIAAC Skills Map data in developing the Adult Literacy Blueprint, a comprehensive plan for coordinated citywide change to address the systemic crisis of low literacy and numeracy in the city. In addition, the Kentucky Career and Technical College System developed a comprehensive data-driven app for workforce pipeline planning using the county-level PIAAC Skills Map data as one of the education pipeline indicators.

This is not the first time NCES is administering PIAAC. NCES collected PIAAC data three times between 2011 and 2017, when the first cycle of this international study was administered in 39 countries. Developed by the Organization for Economic Cooperation and Development (OECD), PIAAC measures fundamental cognitive and workplace skills needed for individuals to participate in society and for economies to prosper. Among these fundamental skills are literacy, numeracy, and digital problem-solving. Data from the first cycle of PIAAC (2011–17) provided insights into the relationships between adult skills and various economic, social, and health outcomes—both across the United States as a whole and for specific populations of interest (e.g., adults who are women, immigrants, older, employed, parents, or incarcerated). The OECD and NCES have published extensively using these data.

The current cycle (Cycle 2) of PIAAC will resemble the first cycle in that interviewers will visit people’s homes to ask if they are willing to answer background questionnaire and take a self-administered test of their skills. However, unlike the first cycle when respondents could respond to the survey on paper or on a laptop, this cycle will be conducted entirely on a tablet. PIAAC is completely voluntary, but each respondent is specifically selected to provide invaluable information that will help us learn about the state of adult skills in the country (participants can also receive an incentive payment for completing the survey).

PIAAC’s background questionnaire includes questions about an individual’s demographics, family, education, employment, skill use, and (new in Cycle 2 and unique to the United States) financial literacy. The PIAAC test or “direct assessment” measures literacy, numeracy, and (new in Cycle 2) adaptive problem-solving skills of adults.1

Each sampled person’s response is not only kept confidential but also “anonymized” before the data are released (so that no one can ever definitively identify an individual from personal characteristics in the datafile).

The international report and data for PIAAC Cycle 2 is scheduled to be released by the OECD in December 2024.

Be sure to follow NCES on TwitterFacebookLinkedIn, and YouTube and subscribe to the NCES News Flash to stay up-to-date on PIAAC report and data releases and resources.

 

By Saida Mamedova, AIR, Stephen Provasnik, NCES, and Holly Xie, NCES


[1] Data is collected from adults ages 16–74 in the United States and ages 16–65 in the other countries.

Rescaled Data Files for Analyses of Trends in Adult Skills

In January 2022, NCES released the rescaled data files for three adult literacy assessments conducted several decades earlier: the 1992 National Adult Literacy Survey (NALS), the 1994 International Adult Literacy Survey (IALS), and the 2003 Adult Literacy and Lifeskills Survey (ALL). By connecting the rescaled data from these assessments with data from the current adult literacy assessment, the Program for the International Assessment of Adult Competencies (PIAAC), researchers can examine trends on adult skills in the United States going back to 1992. This blog post traces the history of each of these adult literacy assessments, describes the files and explains what “rescaling” means, and discusses how these files can be used in analyses in conjunction with the PIAAC files. The last section of the post offers several example analyses of the data.

A Brief History of International and National Adult Literacy Assessments Conducted in the United States

The rescaled data files highlighted in this blog post update and combine historical data from national and international adult literacy studies that have been conducted in the United States.

NALS was conducted in 1992 by NCES and assessed U.S. adults in households, as well as adults in prisons. IALS—developed by Statistics Canada and ETS in collaboration with 22 participating countries, including the United States—assessed adults in households and was administered in three waves between 1994 and 1998. ALL was administered in 11 countries, including the United States, and assessed adults in two waves between 2003 and 2008.

PIAAC seeks to ensure continuity with these previous surveys, but it also expands on their quality assurance standards, extends the definitions of literacy and numeracy, and provides more information about adults with low levels of literacy by assessing reading component skills. It also, for the first time, includes a problem-solving domain to emphasize the skills used in digital (originally called “technology-rich”) environments.

How Do the Released Data Files From the Earlier Studies of Adult Skills Relate to PIACC?

All three of the released restricted-use data files (for NALS, IALS, and ALL) relate to PIAAC, the latest adult skills assessment, in different ways.

The NALS data file contains literacy estimates and background characteristics of U.S. adults in households and in prisons in 1992. It is comparable to the PIAAC data files for 2012/14 and 2017 through rescaling of the assessment scores and matching of the background variables to those of PIAAC.

The IALS and ALL data files contain literacy (IALS and ALL) and numeracy (ALL) estimates and background characteristics of U.S. adults in 1994 (IALS) and 2003 (ALL). Similar to NALS, they are comparable to the PIAAC restricted-use data (2012/14) through rescaling of the literacy and numeracy assessment scores and matching of the background variables to those of PIAAC. These estimates are also comparable to the international estimates of skills of adults in several other countries, including in Canada, Hungary, Italy, Norway, the Netherlands, and New Zealand (see the recently released Data Point International Comparisons of Adult Literacy and Numeracy Skills Over Time). While the NCES datasets contain only the U.S. respondents, IALS and ALL are international studies, and the data from other participating countries can be requested from Statistics Canada (see the IALS Data Files/Publications and ALL Data pages for more detail). See the History of International and National Adult Literacy Assessments page for additional background on these studies. 

Table 1 provides an overview of the rescaled NALS, IALS, and ALL data files.


Table 1. Overview of the rescaled data files for the National Adult Literacy Survey (NALS), International Adult Literacy Survey (IALS), and Adult Literacy and Lifeskills Survey (ALL) 

Table showing overview of the rescaled data files for the National Adult Literacy Survey (NALS), International Adult Literacy Survey (IALS), and Adult Literacy and Lifeskills Survey


What Does “Rescaled” Mean?

“Rescaling” the literacy (NALS, IALS, ALL) and numeracy (ALL) domains from these three previous studies means that the domains were put on the same scale as the PIAAC domains through the derivation of updated estimates of proficiency created using the same statistical models used to create the PIAAC skills proficiencies. Rescaling was possible because PIAAC administered a sufficient number of the same test questions used in NALS, IALS, and ALL.1 These rescaled proficiency estimates allow for trend analysis of adult skills across the time points provided by each study.

What Can These Different Files Be Used For?

While mixing the national and international trend lines isn’t recommended, both sets of files have their own distinct advantages and purposes for analysis.

National files

The rescaled NALS 1992 files can be used for national trend analyses with the PIAAC national trend points in 2012/2014 and 2017. Some potential analytic uses of the NALS trend files are to

  • Provide a picture of the skills of adults only in the United States;
  • Examine the skills of adults in prison and compare their skills with those of adults in households over time, given that NALS and PIAAC include prison studies conducted in 1992 and 2014, respectively;
  • Conduct analyses on subgroups of the population (such as those ages 16–24 or those with less than a high school education) because the larger sample size of NALS allows for more detailed breakdowns along with the U.S. PIAAC sample;
  • Focus on the subgroup of older adults (ages 66–74), given that NALS sampled adults over the age of 65, similar to PIAAC, which sampled adult ages 16–74; and
  • Analyze U.S.-specific background questions (such as those on race/ethnicity or health-related practices).

International files

The rescaled IALS 1994 and ALL 2003 files can be used for international trend analyses among six countries with the U.S. PIAAC international trend point in 2012/2014: Canada, Hungary, Italy, Norway, the Netherlands, and New Zealand. Some potential analytic uses of the IALS and ALL trend files are to

  • Compare literacy proficiency results internationally and over time using the results from IALS, ALL, and PIAAC; and
  • Compare numeracy proficiency results internationally and over time using the results from ALL and PIAAC.

Example Analyses Using the U.S. Trend Data on Adult Literacy

Below are examples of a national trend analysis and an international trend analysis conducted using the rescaled NALS, IALS, and ALL data in conjunction with the PIAAC data.

National trend estimates

The literacy scores of U.S. adults increased from 269 in NALS 1992 to 272 in PIAAC 2012/2014. However, the PIAAC 2017 score of 270 was not significantly different from the 1992 or 2012/2014 scores.


Figure 1. Literacy scores of U.S. adults (ages 16–65) along national trend line: Selected years, 1992–2017

Line graph showing literacy scores of U.S. adults (ages 16–65) along national trend line for NALS 1992, PIAAC 2012/2014, and PIAAC 2017

* Significantly different (p < .05) from NALS 1992 estimate.
SOURCE: U.S. Department of Education, National Center for Education Statistics, National Adult Literacy Survey (NALS), NALS 1992; and Program for the International Assessment of Adult Competencies (PIAAC), PIAAC 2012–17.


International trend estimates

The literacy scores of U.S. adults decreased from 273 in IALS 1994 to 268 in ALL 2003 before increasing to 272 in PIAAC 2012/2014. However, the PIAAC 2012/2014 score was not significantly different from the IALS 1994 score.


Figure 2. Literacy scores of U.S. adults (ages 16–65) along international trend line: Selected years, 1994–2012/14

Line graph showing literacy scores of U.S. adults (ages 16–65) along international trend line for IALS 1994, ALL 2003, and PIAAC 2012/2014

* Significantly different (p < .05) from IALS 1994 estimate.
SOURCE: U.S. Department of Education, National Center for Education Statistics, Statistics Canada and Organization for Economic Cooperation and Development (OECD), International Adult Literacy Survey (IALS), 1994–98; Adult Literacy and Lifeskills Survey (ALL), 2003–08; and Program for the International Assessment of Adult Competencies (PIAAC), PIAAC 2012/14. See figure 1 in the International Comparisons of Adult Literacy and Numeracy Skills Over Time Data Point.


How to Access the Rescaled Data Files

More complex analyses can be conducted with the NALS, IALS, and ALL rescaled data files. These are restricted-use files and researchers must obtain a restricted-use license to access them. Further information about these files is available on the PIAAC Data Files page (see the “International Trend Data Files and Data Resources” and “National Trend Data Files and Data Resources” sections at the bottom of the page).

Additional resources:

By Emily Pawlowski, AIR, and Holly Xie, NCES


[1] In contrast, the 2003 National Assessment of Adult Literacy (NAAL), another assessment of adult literacy conducted in the United States, was not rescaled for trend analyses with PIAAC. For various reasons, including the lack of overlap between the NAAL and PIAAC literacy items, NAAL and PIAAC are thought to be the least comparable of the adult literacy assessments.

Education at a Glance 2021: Putting U.S. Data in a Global Context

International comparisons provide reference points for researchers and policy analysts to understand trends and patterns in national education data and are important as U.S. students compete in an increasingly global economy.

Education at a Glance, an annual publication produced by the Organization for Economic Cooperation and Development (OECD), provides data on the structure, finances, and performance of education systems in 38 OECD countries, including the United States, as well as a number of OECD partner countries. The report also includes state-level information on key benchmarks to inform state and local policies on global competitiveness.

The recently released 2021 edition of the report shows that the United States is above the international average on some measures, such as participation in and funding of postsecondary education, but lags behind in others, such as participation in early childhood education programs. The report also presents some initial comparisons on countries’ responses to the COVID-19 pandemic.

Postsecondary Educational Attainment

The percentage of U.S. 25- to 34-year-olds with a postsecondary degree increased by 10 percentage points between 2010 and 2020, reaching 52 percent, compared with the OECD average of 45 percent (figure 1). Attainment rates varied widely across the United States in 2020, from 33 percent for those living in Nevada to 61 percent for those living in Massachusetts and 77 percent for those living in the District of Columbia.


Figure 1. Percentage of 25- to 34-year-olds with a postsecondary degree, by Organization for Economic Cooperation and Development (OECD) country: 2020

1 Year of reference differs from 2020. Refer to the source table for more details.
SOURCE: OECD (2021), Table A1.2. See Source section for more information and Annex 3 for notes.


In the United States in 2020, 25- to 34-year-old women were more likely than 25- to 34-year-old men to attain a postsecondary education: 57 percent of women had a postsecondary qualification, compared with 47 percent of men, a difference of 10 percentage points. Across OECD countries, the postsecondary education gap between 25- to 34-year-old men and women was wider (13 percentage points) than the gap in the United States (10 percentage points). In 2020, the postsecondary attainment rate of 25- to 34-year-old men in the United States was 8 percentage points higher than the OECD average, whereas the rate of 25- to 34-year-old women in the United States was 5 percentage points higher than the OECD average.

Postsecondary Education Spending

U.S. spending on postsecondary education is also relatively high compared with the OECD average, in both absolute and relative terms. The United States spent $34,036 per postsecondary student in 2018, the second-highest amount after Luxembourg and nearly double the OECD average ($17,065). Also, U.S. spending on postsecondary education as a percentage of GDP (2.5 percent) was substantially higher than the OECD average (1.4 percent). These total expenditures include amounts received from governments, students, and all other sources.

Early Childhood Education

The level of participation in early childhood education programs in the United States is below the OECD average and falling further behind. Between 2005 and 2019, average enrollment rates for 3- to 5-year-olds across OECD countries increased from 77 to 87 percent. In contrast, the rate in the United States remained stable at 66 percent during this time period. Among U.S. states, the 2019 enrollment rates for 3- to 5-year-olds ranged from less than 50 percent in Idaho and North Dakota to 70 percent or more in New York (70 percent), Vermont (76 percent), Connecticut (76 percent), New Jersey (77 percent), and the District of Columbia (88 percent).

COVID-19 Pandemic

Education at a Glance also presents a first look at countries’ responses to the COVID-19 pandemic. The spread of COVID-19 impeded access to in-person education in many countries around the world in 2020 and 2021. By mid-May 2021, 37 OECD and partner countries had experienced periods of full school closure since the start of 2020.

Despite the impact of the crisis on employment, the share of NEETs (those neither in employment nor education or training) among 18- to 24-year-olds did not greatly increase in most OECD and partner countries during the first year of the COVID-19 crisis. On average, the share of 18- to 24-year-old NEETs in OECD countries rose from 14.4 percent in 2019 to 16.1 percent in 2020. However, Canada, Columbia, and the United States experienced an increase of more than 4 percentage points. In the United States, the share of 18- to 24-year-old NEETs increased from 14.6 percent in 2019 to 19.3 percent in 2020.

In 2020, many postsecondary education institutions around the world closed down to control the spread of the COVID-19 pandemic, potentially affecting more than 3.9 million international and foreign students studying in OECD countries. Early estimates show the percentage of international students attending postsecondary institutions in the United States declined by 16 percent between 2020 and 2021.

Browse the full report to see how the United States compares with other countries on these and other important education-related topics and learn more about how other countries’ education systems responded to the COVID-19 pandemic.

 

By Rachel Dinkes, AIR

New International Data Show Large and Widening Gaps Between High- and Low-Performing U.S. 4th- and 8th-Graders in Mathematics and Science

NCES recently released results from the 2019 Trends in International Mathematics and Science Study (TIMSS). TIMSS tests students in grades 4 and 8 in mathematics and science every 4 years. The results show that

  • Across both subjects and grades, the United States scored, on average, in the top quarter of the education systems that took part in TIMSS 2019.
    • Among the 64 education systems that participated at grade 4, the United States ranked 15th and 8th in average mathematics and science scores, respectively.
    • Among the 46 education systems that participated at grade 8, the United States ranked 11th in average scores for both subjects.
  • On average, U.S. scores did not change significantly between the 2011 and 2019 rounds of TIMSS.

Average scores are one measure of achievement in national and international studies. However, they provide a very narrow perspective on student performance. One way to look more broadly is to examine differences in scores (or “score gaps”) between high-performing students and low-performing students. Score gaps between high performers and low performers can be one indication of equity within an education system. Here, high performers are those who scored in the 90th percentile (or top 10 percent) within their education system, and low performers are those who scored in the 10th percentile (or bottom 10 percent) within their education system.

In 2019, while some education systems had a higher average TIMSS score than the United States, none of these education systems had a wider score gap between their high and low performers than the United States. This was true across both subjects and grades.

Figure 1 shows an example of these findings using the grade 8 mathematics data. The figure shows that 17 education systems had average scores that were higher or not statistically different from the U.S. average score.

  • Of these 17 education systems, 13 had smaller score gaps between their high and low performers than the United States. The score gaps in 4 education systems (Singapore, Chinese Taipei, the Republic of Korea, and Israel) were not statistically different from the score gap in the United States.
  • The score gaps between the high and low performers in these 17 education systems ranged from 170 points in Quebec, Canada, to 259 points in Israel. The U.S. score gap was 256 points.
  • If you are interested in the range in the score gaps for all 46 education systems in the TIMSS 2019 grade 8 mathematics assessment, see Figure M2b of the TIMSS 2019 U.S. Highlights Web Report, released in December 2020. This report also includes these results for grade 8 science and both subjects at the grade 4 level.

Figure 1. Average scores and 90th to 10th percentile score gaps of grade 8 students on the TIMSS mathematics scale, by education system: 2019

NOTE: This figure presents only those education systems whose average scores were similar to or higher than the U.S. average score. Scores are reported on a scale of 0 to 1,000 with a TIMSS centerpoint of 500 and standard deviation of 100.

SOURCE: International Association for the Evaluation of Educational Achievement (IEA), Trends in International Mathematics and Science Study (TIMSS), 2019.


From 2011 to 2019, U.S. average scores did not change significantly. However, the scores of low performers decreased, and score gaps between low and high performers grew wider in both subjects and grades. In addition, at grade 8, there was an increase in the scores of high performers in mathematics and science over the same period. These two changes contributed to the widening gaps at grade 8.

Figure 2 shows these results for the U.S. grade 8 mathematics data. Average scores in 2011 and 2019 were not significantly different. However, the score of high performers increased from 607 to 642 points between 2011 and 2019, while the score of low performers decreased from 409 to 385 points. As a result, the score gap widened from 198 to 256 points between 2011 and 2019. In addition, the 2019 score gap for grade 8 mathematics is significantly wider than the gaps for all previous administrations of TIMSS.


Figure 2. Trends in average scores and selected percentile scores of U.S. grade 8 students on the TIMSS mathematics scale: Selected years, 1995 to 2019

* p < .05. Significantly different from the 2019 estimate at the .05 level of statistical significance.

NOTE: Scores are reported on a scale of 0 to 1,000 with a TIMSS centerpoint of 500 and standard deviation of 100.

SOURCE: International Association for the Evaluation of Educational Achievement (IEA), Trends in International Mathematics and Science Study (TIMSS), 1995, 1999, 2003, 2007, 2011, 2015, 2019.


These TIMSS findings provide insights regarding equity within the U.S. and other education systems. Similar results from the National Assessment of Educational Progress (NAEP) show that mathematics scores at both grades 4 and 8 decreased or did not change significantly between 2009 and 2019 for lower performing students, while scores increased for higher performing students. More national and international research on the gap between high- and low-performing students could help inform important education policy decisions that aim to address these growing performance gaps.

To learn more about TIMSS and the 2019 U.S. and international results, check out the TIMSS 2019 U.S. Highlights Web Report and the TIMSS 2019 International Results in Mathematics and Science. A recording is also available for a RISE Webinar from February 24, 2021 (What Do TIMSS and NAEP Tell Us About Gaps Between High- and Low-Performing 4th and 8th Graders?) that explores these topics further. 

 

By Katie Herz, AIR; Marissa Hall, AIR; and Lydia Malley, NCES