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Frequently Asked Questions

In addition to the following questions about PIAAC, more FAQs about international assessments are available at:

What is assessed in PIAAC?

PIAAC is designed to assess adults over a broad range of abilities—from simple reading to complex problem solving skills. All countries that participate in PIAAC will assess the domains of literacy and numeracy in both a paper-and-pencil mode and a computer-administered mode. In addition, countries may assess problem solving administered on a computer as well as components of reading (administered only in paper-and-pencil format). The U.S. will assess all four domains.

How does PIAAC select a representative sample of adults?

Countries that participate in PIAAC must draw a sample of individuals ages 16 to 65 that represent the entire population of adults living in households in the country. Some countries draw their samples from their national registries of all persons in the country; others draw their samples from census data. In the United States, a nationally representative household sample was drawn from the most current Census Bureau population estimates.

The U.S. sample design employed by the PIAAC is generally referred to as a four-stage stratified area probability sample. This method involves the selection of (1) primary sampling units (PSUs) consisting of counties or groups of contiguous counties, (2) secondary sampling units (referred to as segments) consisting of area blocks, (3) dwelling units (DUs), and (4) eligible persons (ultimate sampling unit) within DUs. Random selection methods are used, with calculable probabilities of selection at each stage of sampling. This sample design ensures the production of reliable statistics for a minimum of 5,000 completed cases.

How does PIAAC differ from international student assessments?

As an international assessment of adult competencies, PIAAC differs from student assessments in several ways. PIAAC assesses a wide range of ages (persons between the ages of 16 and 65) whereas student assessments target a specific age (e.g., 15-year-olds in the case of PISA) or grade (e.g., grade 4 in PIRLS). PIAAC is a household assessment (i.e., an assessment administered in individuals' homes), whereas the international student assessments (PIRLS, PISA, and TIMSS) are conducted in schools. The skills that are measured in each assessment also differ based on the goals of the assessment. Both TIMSS and PIRLS are curriculum-based and are designed to assess what students have been taught in school in specific subjects, such as science or mathematics, using multiple-choice and open-ended test questions. In contrast, PIAAC and PISA are “literacy” assessments, designed to measure performance in certain skill areas at a broader level than school curricula. So while TIMSS and PIRLS aim to assess particular academic knowledge that students are expected to be taught at particular grades, PISA and PIAAC encompass a broader set of skills that students and adults have acquired throughout life.

How do PIAAC and PISA compare?

PISA and PIAAC both emphasize knowledge and skills in the context of everyday situations, asking students and adults to perform tasks that involve interpretation of real-world materials as much as possible. PISA is designed to show the knowledge and skills 15-year-olds have accumulated within and outside of school. It is intended to provide insight into what students who are about to complete compulsory education and continue with further education or potentially enter the workforce know and are able to do. PIAAC focuses on adults who are already eligible to be in the workforce, and aims to measure the set of literacy skills an individual needs to have in order to function successfully in society. Therefore, PIAAC is not measuring the academic skills or knowledge adults may have learned in school. The PIAAC assessment focuses on tasks adults may encounter in their lives at home, work, or in their community.

How does PIAAC differ from earlier adult literacy assessments, like IALS and ALL?

PIAAC expands on knowledge and experiences gained from previous international adult assessments—the International Adult Literacy Survey (IALS) and the Adult Literacy and Lifeskills Survey (ALL). PIAAC improves and expands on these previous assessments' cognitive frameworks, and has added an assessment of problem solving via computer, which was not a component of the previous studies. In addition, PIAAC is capitalizing on prior experiences with IALS and ALL in its approach to survey design and sampling, measurement, data collection procedures, data processing, and weighting and estimation. Finally, the most significant difference between PIAAC and previous large-scale literacy assessments, including IALS and ALL, is that PIAAC is administered on laptop computers, and is designed to be a computer-adaptive assessment so respondents will receive groups of items targeted to their performance levels.


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