Jyväskylä Longitudinal Study of Personality and Social Development (JYLS)
Jyväskylä Longitudinal Study of Personality and Social Development was initiated as Lea Pulkkinen's doctoral dissertation in 1968. Since then, the study has continued to follow the same individuals for over 40 years. When the project was launched, 369 eight-year-old children participated in the research. They were randomly selected among second-graders in primary school. After the first research, data have been collected when the respondents have been 14, 20, 27, 33, 36, 42, 50, and 60 years old. The latest data collection started in 2020.
When the respondents were still in school, the principal methods of data collection were teacher ratings and peer nominations on the pupils' social behaviour. In adulthood, the data collection methods have mostly been interviews and questionnaires. At the ages of 42 and 50, the respondents also participated in medical examinations and laboratory tests. The research themes have included socioemotional development and personality, education and career, family of origin and one's own family, health behaviour and health, and social adjustment. The measures used in the JYLS studies are presented in the methods table.
The number of participants has been high during the whole project: each round of data collection has yielded a response rate of 70% or more among the original sample. The sample has been proven to be representative of its age group in terms of family relations, education, occupational status, and unemployment.
The Academy of Finland has been the main source of funding since 1986. In addition, the Finnish Cultural Foundation funded the project in 1986. The research was conducted by university students and officials at the University of Jyväskylä up to 1986. The Jyväskylä Longitudinal Study of Personality and Social Development (JYLS) was one of the three major longitudinal studies included in the Human Development and Its Risk Factors Programme, which was approved as the Centre of Excellence for the years 1997-1999 and 2000-2005 by the Academy of Finland and the Ministry of Education. In 2009, the data collection was financed by the Academy of Finland's funding granted to Lea Pulkkinen (decision no. 127125) and Katja Kokko (decision no. 118316). The project is located at the Gerontology Research Center at the University of Jyväskylä and led by Docent and Research Director Katja Kokko.