While NAAL does not measure "illiteracy" per se, adults who cannot read well enough to attempt or to correctly answer the minimum number of basic literacy questions in the 2003 NAAL may be classified as not literate in English.
A number of steps were taken to preserve comparability between the 1992 NALS and 2003 NAAL. First, almost half of the 2003 sample questions are taken from the 1992 assessment. Second, the new 2003 test questions are similar to those used in 1992. Third, NAAL uses the same sampling and data collection procedures as NALS to ensure that NAAL participants are similar to those surveyed in 1992. Fourth, 2003 results are along the same literacy scales as those used in 1992—prose, document, and quantitative. Finally, the 1992 NALS data have been reanalyzed along new, 2003 NAAL performance levels.
NCES does not plan to establish grade-level equivalents because they are unsuitable for characterizing the skills of adults (who often have uneven skills across different literacy areas).
NAAL questions reflect the tasks and stimulus materials that adults encounter in daily life. A school-based assessment like the National Assessment of Educational Progress (NAEP) focuses more directly on a participant's ability to read, and less on a participant's ability to apply what they have read to accomplish everyday literacy goals. Also, NAAL is 100 percent open-ended (requires short-answer responses), and questions are placed before the stimulus material so that respondents have to search the text for information. School-based assessments like NAEP have a percentage of multiple-choice questions and answers, and questions are placed after the stimulus material, so that students have to read the entire text for full comprehension before answering the question.
In terms of scoring, NAAL differs from school-based assessments because it scores responses as partially correct if they lead to partial accomplishment of the task. NAAL offers greater insight into the correlation between participants' skill levels and their ability to function in society than does a school-based assessment.
The same year that NAAL was conducted (2003), the Adult Literacy and Lifeskills Survey (ALL) was conducted in six countries: Bermuda, Canada, Italy, Norway, Switzerland, and the United States. ALL provided comparative international information about the prose and document skills, as well as the numeracy skills, of the adult populations in these countries. For a comparison of NAAL and ALL, please click here.
The most recent international assessment of adult literacy is the Program for the International Assessment of Adult Competencies (PIAAC), a large-scale international assessment conducted across 24 countries in 2011-12. The PIAAC measured adult skills in literacy, numeracy, and problem solving in technology-rich environments.
PIAAC improved upon and expanded on the cognitive frameworks of previous large-scale literacy assessments, including NAAL and ALL. Some improvements included:
Because of these differences, PIAAC introduced a new set of scales to measure adult literacy, numeracy, and problem solving. Some scales from previous adult assessments, including NAAL and ALL, have been mapped to the PIAAC scales so that performance can be measured over time.