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. More information about NALS can be found here.
In 2003, NCES conducted its largest household assessment of adult literacy skills in the United States: 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 and NAAL each presented a snapshot of the condition of literacy for the U.S. population as a whole and among key population subgroups and, when looked at in combination, changes in literacy over time. More information about NAAL can be found here.
The IALS study, developed by Statistics Canada and ETS in collaboration with participating national governments, 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. More information about IALS can be found here.
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. More information about ALL can be found here.
In 2022, NCES released the data with the rescaled literacy (NALS, IALS, and ALL) and numeracy (ALL) scores on the three previous studies. This data facilitates the analysis of national trend data across NALS and PIAAC and the analysis of international trend data across the three international surveys – IALS, ALL, and PIAAC. The assessment domains from these three previous studies were rescaled to match the statistical models used in creating PIAAC scores for literacy and, in the case of ALL, numeracy. Rescaling was possible because PIAAC administered a sufficient number of the same test questions used in NALS, IALS, and ALL. Rescaled plausible values for literacy for NALS, IALS, and ALL and numeracy for ALL, along with some trend background questionnaire items, allow for trend analysis with the U.S. PIAAC results. The restricted-use data files can be found on the NALS Data Files, IALS Data Files, and ALL Data Files publication pages.
PIAAC seeks to ensure continuity with these previous surveys, expand on their quality assurance standards, extend the definitions of literacy and numeracy, present the problem-solving domain to emphasize skills used in technology-rich environments, and provide more information about individuals with low levels of literacy by assessing reading component skills.Overview of Previous International and National Assessments of Adult Skills
|Assessment||Year(s)||U.S. Sample Size||Population||Domains||National/International Survey|
|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)||2012–2107 (Cycle I)||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 in prisons||Literacy, Numeracy, Problem solving in technology-rich environments||International; 39 countries participated|