The origins of the international adult literacy assessment program, which began with the International Adult Literacy Survey (IALS) and continues with Program for the International Assessment of Adult Competencies (PIAAC), lie to a large extent in the pioneering work of national adult literacy assessments undertaken in the United States and Canada in the early 1990s.
In the United States, the National Adult Literacy Survey (NALS) was conducted in 1992 by the National Center for Education Statistics (NCES). NALS assessed a nationally representative sample of adults residing in households as well as a sample of adults in prisons.
NCES conducted its largest household assessment of adult literacy skills in the United States in 2003: the National Assessment of Adult Literacy (NAAL). NAAL sampled adults representing the entire population of U.S. adults residing in households and also sampled adults representing the population in federal and state prisons. NALS (1992) and NAAL (2003) each provided a snapshot of literacy levels for the entire U.S. population as well as key population subgroups. When viewed together, they can show how U.S. literacy has changed over time.
The IALS study, developed by Statistics Canada and ETS in collaboration with participating countries, adopted and refined the NALS methodology, scales, and literacy frameworks. Twenty-two countries, including the United States, administered the IALS study in three waves between 1994 and 1998.
Concurrent with the further waves of IALS data collection, Statistics Canada sponsored work on the development of a successor to IALS with the goal of measuring a broader range of adult skills than had been covered previously. The Adult Literacy and Lifeskills Survey (ALL) sought to improve on IALS by developing standards and quality assurance measures that would minimize sources of survey variability and, therefore, render the survey results more comparable. Eleven countries, including the United States, administered the ALL study in two waves between 2003 and 2008.
The purpose of the PIAAC study is to ensure continuity with previous adult literacy surveys, expand on their quality assurance and technical standards, and extend the definitions of literacy and numeracy. PIAAC was developed by the Organization for Economic Cooperation and Development (OECD), and PIAAC Cycle 1 was conducted in three separate rounds between 2012 and 2017 in 39 participating countries, with over 245,000 adults interviewed. During PIAAC Cycle 1, the United States conducted three rounds of data collection. The first round, in 2012, with a sample size over 5,000, was a nationally representative sample. The second round, in 2014, oversampled young adults and unemployed adults, supporting more accurate and reliable national estimates for these subgroups. The second round also sampled adults representing the population in federal and state prisons. The third round, in 2017, with a sample size over 3,000, was a nationally representative sample.
Both PIAAC Cycle 1 household data collection and the PIAAC prison data collection included a comprehensive background questionnaire (BQ) and a direct assessment. The PIAAC BQ gathered detailed policy-relevant information on participants to examine how skills vary among different subgroups, how they are acquired, how they are used at work and at home, and their impact on various life outcomes. The direct assessment measured literacy and numeracy skills of adults and presented the digital problem-solving domain to emphasize skills used in technology-rich environments. It also provided more information about individuals with low levels of literacy by assessing reading component skills. In addition, PIAAC was the first large-scale international assessment to be administered on laptop computers, allowing for automatic scoring and potential for log file analysis. With the introduction of the computer-based assessment, PIAAC was also the first adult skills assessment to introduce adaptive features in the BQ and the direct assessment.
During the second round of PIAAC Cycle 1 in 2014, the United States conducted a separate study sampling 1,300 inmates (ages 18–74) representing the U.S. adult population in federal and state prisons. While inmates were administered the same direct assessment, the prison BQ was specifically designed to address the experiences and needs of the inmate population. The results allow for a direct comparison between the adults in the household and prison, and also provided rich data on the background of incarcerated adults.
PIAAC Cycle 2 was conducted in 2023 in 31 countries. A nationally representative sample of over 4,500 adults participated in the United States. PIAAC Cycle 2 introduced a number of innovations while maintaining trend continuity. These innovations included updated frameworks of the BQ and direct assessments to better reflect the current demands on adults found in digital environments in today’s society. Updates to the direct assessment included the introduction of adaptive problem solving, which measures adults’ dynamic and adaptive problem-solving strategies and replaced Cycle 1’s digital problem-solving domain, and the introduction of numeracy components to provide more detailed information about adults with low numeracy skills.
The continuity of PIAAC on adult skills, with a sufficient number of the same test questions used in NALS, IALS, and ALL administered in PIAAC, allows for trend analysis across these studies. More details on the rescaled data files can be found on the PIAAC Data Files page and the blog Rescaled Data Files for Analyses of Trends in Adult Skills.
Overview of Previous International and National Assessments of Adult SkillsAssessment | Year(s) | U.S. Sample Size | Population | Domains | National/International Survey |
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National Adult Literacy Survey (NALS) | 1992 | Approximately 26,000, including more than 1,100 inmates and the approximately 1,000 adults surveyed in 12 states | Adults 16 and older, in households and prisons | Prose literacy, Document literacy, Quantitative literacy | National; in addition,12 states participated in the State Adult Literacy Survey (SALS) to report state-level results comparable to the national data |
International Adult Literacy Survey (IALS) | 1994–1998 | Approximately 3,000 | Adults 16–65, in households | Prose literacy, Document literacy, Quantitative literacy | International; 22 countries participated |
National Assessment of Adult Literacy (NAAL) | 2003 | Approximately 19,700, including about 1,200 inmates, and approximately 1,000 adults surveyed in 6 states | Adults 16 and older, in households and prisons | Prose literacy, Document literacy, Quantitative literacy | National; in addition, 6 states participated in the State Assessment of Adult Literacy (SAAL) to report state-level results comparable to the national data |
Adult Literacy and Lifeskills Survey (ALL) | 2003–2008 | Approximately 3,400 | Adults 16–65, in households | Document literacy, Prose literacy, Numeracy | International; 11 countries participated |
Program for the International Assessment of Adult Competencies (PIAAC) |
2012–2017 (Cycle 1); 2014 (prison study)
|
Approximately 13,600, including about 5,000 in 2012, over 3,600 in 2014, and over 3,600 in 2017 in households, and about 1,300 inmates | Adults 16–74, in households and adults 18–74 in prisons | Literacy, Numeracy, Problem solving in technology-rich environments | International; 39 countries participated; prison study was a national study |
2023 (Cycle 2) | Approximately 4,600 in households | Adults 16–74, in households | Literacy, Numeracy, Adaptive Problem Solving | International; 31 countries participated |