The IALS represented a first attempt at undertaking a large-scale household-based assessment of adult literacy skills at the international level. It was conducted as a household survey that covered the civilian, non-institutionalized population aged 16-65. Data collection for the IALS project took place between 1994 and 1998, depending on which of the survey cycles a country participated.16
Countries were encouraged to field sample sizes large enough to yield 3,000 completed cases after non-response, so that secondary analysis and estimates of literacy profiles could be obtained reliably. Although the common target population was people aged 16-65, individual countries were free to sample younger or older adults. Canada, Sweden and Switzerland sampled persons at least 16 years of age but with no upper limit, while the Netherlands sampled persons aged 16-74, and Australia sampled those aged 15-74. Chile also took this opportunity, including young adults 15 years of age.
During the development stage of the survey, countries were provided with a "master" English-language version of the background questionnaire and task booklets. With respect to the background questionnaire, the master copy clearly indicated which questions were optional or mandatory and whether and how countries could adapt response categories to country-specific needs. Moreover, as a result of the pilot test, any items that failed the study's standards for psychometric equivalence were identified and countries requested to verify possible translation, adaptation or scoring problems. With this additional information in hand the countries were able to further improve the adaptations and translations of their instruments.
Each respondent completed the questionnaire and took the test, of approximately one-hour in duration, during a personal interview. These interviews and tests were conducted in people's homes in a neutral, non-pressuring manner. Interviewer training and supervision was to be provided, emphasizing the selection of one person per household (if applicable), the selection of one of the seven main task booklets (if applicable), the scoring of the core task booklet, and the assignment of status codes.
The background questionnaire contained a range of questions concerning, for example, the respondent's demographic characteristics, family background, labor force status, reading habits at work and at home, participation in adult education and training, and self-reports on literacy ability.
16. The survey description provided in this annex draws on material from the IALS international reports published previously by OECD and Statistics Canada (1995 and 2000), see references in Annex C.