Volume 4, Issue D ::: April 2001
Describing the Longitudinal Study of Adult Learning
NCSALL's Longitudinal Study of Adult Learning (LSAL) is a panel study. This type of longitudinal study follows a fixed sample of individuals (the panel) over time. LSAL's data collection involves in-home, in-depth interviews and cognitive assessments of 979 adults, age 18-44, living in the Portland, OR, metropolitan area, who do not have a high school diploma or equivalent, and are proficient English speakers. The participants are being periodically interviewed and assessed over seven years, regardless of whether they enter, stay in, or leave adult education programs, or move from one geographical area to another.
The study was designed to answer fundamental research questions at the center of adult education, learning, and literacy development.
To what extent do adults' literacy abilities continue to develop after they leave school?
What life experiences are associated with adult literacy development? How do formally organized education programs contribute to the growth over time in individuals' skills and knowledge? Workplace learning? In other learning contexts and activities?
What are adult learners' patterns of participation over time in literacy training and education? In other learning contexts and activities?
What is the impact of adult literacy development on social and economic outcomes?
Many longitudinal studies use national samples, random samples drawn from across the United States, because findings done with such samples are widely applicable to broad questions of policy. Using a national sample is expensive and logistically difficult. The LSAL draws on a local population, so the findings cannot necessarily be generalized to other areas. One advantage of a local sample is that the population shares a relatively homogeneous context. For example, with a local sample it may be easier to understand how differences among individuals' literacy abilities influence their labor market activities than with a national sample in which individuals are not representative of any particular locale.
The LSAL uses a comparison group design: about half the participants, none of whom had received a high school degree or a certificate of General Educational Development (GED) at the onset of the study, are program participants and half are nonparticipants. This allows us to trace the differences we may observe between the experiences over time of the two groups' back to their participation status. Statistical methods will be used to control for the potentially confounding effects of other influences on comparisons between program participants and nonparticipants.
Each wave of data collection consists of an in-home interview followed by cognitive assessments: a standardized functional literacy assessment as well as measures of vocabulary (vocabulary tests are only administered during the first two waves). LSAL chose the Document Literacy scale of the Test of Applied Literacy Skills (TALS) developed by the Educational Testing Service. Administered in a constructed-response rather than multiple-choice format, the TALS assesses adults' abilities to extract and process written information in a variety of everyday document formats. It is easy to administer and has known psychometric properties suitable for use in a panel study. It was used in the National Adult Literacy Survey, the International Adult Literacy Survey (IALS), and numerous state-level surveys of adult literacy, making the LSAL comparable to those studies. Because literacy programs do not use it, study participants will not have prior experience with it.
Although we have a strong interest in the learning experience of speakers of English as a second language, resource limitations required the LSAL to exclude people from the study who did not speak English proficiently. We hope to include such speakers in future studies. Proficient speakers of English as a second language were included in the study. Participants were recruited by randomly calling telephone numbers in the Portland metropolitan area. Part of the screening process was to determine whether or not the otherwise eligible person had enough English comprehension and expressive ability to participate in the lengthy face-to-face interview. Of the eventual sample, 90% were born in the United States and 88% speak English as a first language, six percent spoke Spanish as a first language, and six percent spoke another first language.