IALS Study Details

What does IALS measure?

The IALS study defined literacy as "using printed and written information to function in society, to achieve one's goals, and to develop one's knowledge and potential" (NCES IALS Technical Report).  IALS measured three domains of literacy:

  1. Prose Literacy: the knowledge and skills needed to understand and use information from texts including editorials, news stories, poems, and fiction.
  2. Document Literacy: the knowledge and skills required to locate and use information contained in various formats, including job applications, payroll forms, transportation schedules, maps, tables, and graphics.
  3. Quantitative Literacy: the knowledge and skills required to apply arithmetic operations, either alone or sequentially, to numbers embedded in printed materials, such as balancing a checkbook, calculating a tip, completing an order form, or determining the amount of interest on a loan from an advertisement.

The three domains each encompass a common set of skills relevant for diverse tasks. Scores were reported for each domain.

Proficiency Levels

IALS and the U.S. National Adult Literacy Survey (NALS)

IALS adopted its methodology and scales from the 1992 U.S. National Adult Literacy Survey (NALS). The definition of literacy used in IALS was developed and refined from that used in the 1992 NALS. IALS also adopted a number of items from NALS in order to make the assessments comparable. On the prose and document scales, 50 items from NALS were used in IALS. On the quantitative scale, 26 items were carried over, for a total of 76 NALS items in IALS.  For more information on NALS, visit the collection of NALS publications on the NAAL website.

How was IALS administered?

IALS consisted of two components: a background questionnaire, about 20 minutes in length, and an assessment, which was not timed. The assessment consisted of about 45 assessment items (see Sample Items).  Trained interviewers administered both components to participants in their homes. Participants were selected from a nationally representative sample and in some countries and regions they received a monetary incentive for participating1. Respondents were first asked to complete the background questionnaire, which was designed to collect general demographic information about participants (such as sex, age, race/ethnicity) as well as more targeted information related to their educational experiences, labor market experiences, and literacy related activities.

Once the background questionnaire was completed, the interviewer presented a booklet containing six simple tasks ("Core tasks"). If a respondent could not complete two of these tasks correctly, the interview was adjourned. Respondents who completed two or more of these tasks correctly were given a booklet with a larger variety of tasks drawn from a pool of 114 items grouped into blocks. They were encouraged to attempt each task, but there was no time limit and the survey was voluntary.

To reduce respondents' time burden without sacrificing good representation of the content domain, each respondent was administered only a fraction of the pool of tasks through a procedure known as matrix sampling. Each booklet was designed to take about 45 minutes to complete and contained three blocks that represented about 45 items. Overall, the assessment drew from seven blocks, each requiring approximately the same amount of response time and covering all three literacy domains (prose, document, and quantitative). IALS data were collected by participating countries in successive cycles of data collection between 1994 and 1998, using nationally representative samples of the adult population aged 16-65. In the United States, a nationally representative sample of 3,053 adults aged 16–65 participated in IALS. The U.S. data collection took place in October and November 1994.

For more information on the administration go to the NCES IALS Technical Report.

1 Two countries provided incentives: Germany gave away lottery tickets and Sweden gave a small reward. The United States did not offer any incentive in IALS. Source: https://nces.ed.gov/pubsearch/pubsinfo.asp?pubid=98053, page 94.

Sample Design

Each country participating in IALS agreed to design a high-quality probability sample representing the adult non-institutional civilian population aged 16 to 65. In the United States, respondents were selected from a sample of individuals in housing units who were completing their final round of interviews in the Current Population Survey (CPS).

The CPS is a large-scale, continuous household survey of the non-institutional civilian population, aged 15 and older, conducted by the Bureau of Labor Statistics. The CPS sample is selected using a stratified multi-stage design. Housing units in the CPS sample used for IALS were derived from the 1980 Census and from lists of new construction, when available.

The IALS sample was limited to 60 of the CPS's 729 primary sampling units (PSUs). Within these 60 PSUs, participants were selected using a proportional probability sampling procedure. The final sample size for the United States was 3,053. For more information the sample design of IALS, please see the NCES IALS Technical Report.

 

Data Files/Publications

  1. Literacy, Economy, and Society: Results of the First International Adult Literacy Survey
  2. Literacy Skills for the Knowledge Society: Further Results from the International Adult Literacy Survey
  3. Literacy in the Information Age: Final Report of the International Adult Literacy Survey
  4. NCES U.S. IALS Restricted-Use Data File
    The IALS U.S. 1994 restricted-use file (RUF) with rescaled literacy scores (found here) contains individual unit data including both responses to the background questionnaire and the cognitive assessment from the U.S. IALS data collection, completed in 1994. The file contains rescaled plausible values for literacy and some trend background questionnaire items to allow for trend analysis with the U.S. Program for the International Assessment of Adult Competencies (PIAAC) data. The RUF with rescaled scores can be accessed through a restricted use license agreement with the National Center for Education Statistics.
  5. Stats Canada's International IALS Public-Use Data Files
    For analysis with IALS data from other countries, rescaled public-use micro data files from IALS that include the sample from all of the countries that participated in the survey can be obtained from Statistics Canada by sending a request for "rescaled public-use data files for IALS (1994-1998)" to infostats@statcan.gc.ca. Users will then be signed up to an Electronic File Access (EFT) service where they can download the requested files through the EFT Portal.

Sample Items

Items from IALS have not been released for disclosure concerns, as unreleased items can be used in current and future adult literacy assessments, which allows for trend analysis with IALS. However, the items contain examples of the tasks that were developed for the pilot study. These tasks were not used for the main survey, but they provide an idea of the types of tasks used in the final selection of items. The tables accompanying these tasks provide a broad analysis of each item, the theoretical difficulty summary score that was assigned (ranging from 5, easiest, to 19, most difficult), and the difficulty statistics that were gathered during the pilot study.

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Country Participation in IALS by Year

Eight countries from around the world participated in IALS in 1994.
Those countries are:

  • Canada
  • Germany
  • Ireland
  • The Netherlands
  • Poland
  • Sweden
  • Switzerland
  • United States

In 1996 five additional countries or territories participated in IALS.
Those countries are:

  • Australia
  • Belgium (Flemish)
  • Great Britain
  • New Zealand
  • Northern Ireland

Finally, in 1998 nine additional countries or regions participated in IALS.
Those countries are:

  • Chile
  • Czech Republic
  • Denmark
  • Finland
  • Hungary
  • Italy
  • Norway
  • Slovenia
  • Switzerland (Italian-speaking region)

Partners

NCES worked with the following agencies or organizations to carry out the International Adult Literacy Survey (IALS) in the United States: