The Beginning in 1968
The DLSY was initiated in the midle of the 1960'ies by Professor Erik Jørgen Hansen on the basis of an earlier survey of the 14-20 year olds educational situation in 1965 (Hansen 1968). The first survey took place in 1968 and interviewed the cohort that was in 7th grade in 1967 and 1968. They were interviewed for the first time in the end of 7th grade (may 1968). 3151 students participated in the survey from 152 classes across the country. The students were approximately 14 years old. 21 were born in 1952 or before (1 pct.), 361 in 1953 (12 pct.), 2464 in 1954 (83 pct.) and 146 in 1955 (5 pct.). The year of birth is unknown for 159.
Since the first round of interviews in 1968 the participants have been reinterviewed in 1970, 1971, 1973, 1976, 1992, 2001 and latest in 2004, when they were about 50 years old. The DLSY has thus followed the same group of danes for more than 35 years. Further, the parents have been interviewed in 1969.
From the original group of 3151 participants in the 1968 survey, 2505 or about 80 pct was interviewed in the 2001 round. The very high response rate has contributed to the DLSY becomming one of the best cohort studies in the world. A cohort study is a type of survey, where you follow a group of people over time that are all born at the same time.
The Danish Longitudinal Survey of Youth - Children (DLSY-C)
The DLSY-C survey is a new survey that includes all children of the original participants in the DLSY survey. The participants in the DLSY-C survey is the third generation of respondents from the same family, that has participated in the same study. You can read more about the DLSY-C survey here.
Apart from the DLSY there are very few studies that contain information on three generations from the same family. This makes the DLSY unique in both a danish and international context.
Luckily the DLSY is not the only of its kind. In Denmark there is also the The Danish Longitudinal Survey of Children (DALSC) (follows a cohort born in 1995). Internationally especially England and USA has a tradition for making cohort studies.
In England there is the National Child Development Study (follows a cohort born in 1958), the British Cohort Study (follows a cohort born in 1970) and the Millenium Cohort Study (follows a cohort born in 2000/2001).
In USA the is the Wisconsin Longitudinal Study (follows a cohort born in 1939) andthe National Longitudinal Survey of Youth 1979/1997 (follows several cohorts).