Jyväskylä Longitudinal Study of Personality and Social Development (JYLS)
The Jyväskylä Longitudinal Study of Personality and Social Development (JYLS) began as Lea Pulkkinen's doctoral dissertation in 1968. Professor Pulkkinen oversaw the project until 2012. Since 2013, Research Director Katja Kokko has acted as the Principal Investigator. In the study, same participants (N = 369; born 1959) have been followed from age 8 to age 60. The main aim of the JYLS has been to examine continuity and interaction in different areas of life: socioemotional behaviour and personality, education and work career, family of origin and one's own family, health behaviour and health, and social adjustment and delinquency.
The participants, born mostly in 1959, were 8-year-old second-grade pupils when the study began. The sample was drawn from 12 complete school classes (196 boys, 173 girls) chosen randomly from the schools of a medium-sized town in Central Finland. The same individuals have been followed up until the age of 50. After initial data collection, data has been collected when the participants were 14, 20, 27, 33, 36, 42, 50 and 60 years old. The newest data collection began in 2020. Primary methods of data collection were peer nomination and teacher ratings when the participants were at school age and interviews and questionnaires after the participants became adults. Additionally, medical examinations were conducted when the participants were 42 and 50 years old.
The number of participants has remained high throughout the project: since the participants reached adulthood, each data wave yielded information on at least 70% of the original sample.
More information on data waves and methods used can be found on the web pages of the Department of Psychology at the University of Jyväskylä.
Organisation and funding
Since 1986, the main funder of the project has been the Academy of Finland. The Finnish Cultural Foundation also provided funding for the study in 1986. From its inception until 2013, the JYLS project belonged to the Department of Psychology, University of Jyväskylä. From 2014 onwards, it has been located at the Gerontology Research Center and the Department of Health Sciences at the University of Jyväskylä.
The Data Archive contains the archive versions of the JYLS data. Archive version refers to the data as they were coded, for example, from questionnaires. One archived dataset usually consists of data collected in one collection wave. Members of the research project use working copies of the data for analyses and these versions may contain imputed values or data originating from several collection waves or methods.
The JYLS project has provided extensive documentation on the variables used in the data in MS Word file format, both in Finnish and English. For long-term preservation, documentation provided by the project in Finnish has been converted into DDI-XML format.
List of publications based on JYLS data can be found on the project website.
Metadata (e.g. description of contents, sampling procedure, authors) of each dataset are freely accessible in the Aila Data Catalogue of FSD.
Data Application Procedure
The JYLS data may be obtained for research purposes, for example, for international publications or doctoral theses, but not for teaching purposes or for Bachelor's, Master's or licentiate theses. Because the data are still in active use by the original research team, other users need Research Director Katja Kokko's permission to gain access. The research team decides whether to grant access to the data or not on a case-by-case basis. In practice, the data are generally used in cooperation with researchers from the research team.
The JYLS data have a special access application procedure that differs from the procedure normally used for data archived at the FSD. The application procedure has two stages:
- The applicant fills in the Access Application on Aila Data Service. The Data Archive reviews the application, ensuring that the proposed purpose of use is in line with the above mentioned principles. If approved, the Archive sends the applicant the codebooks/data guides, which include, for example, questionnaires, variable lists, frequencies and methods table.
- The applicant produces a detailed research plan specifying the variables needed, using the material received from the Archive. The applicant sends this research plan directly to Research Director Katja Kokko. If the application and research plan are approved, the research team sends working copies of the requested variables directly to the applicant.