Baseline data and follow-up studies

1983 - Baseline data collection 

Baseline data was collected in Tampere in the spring of 1983. The target population was all students studying in Finnish speaking 9th grades of Tampere’s comprehensive schools. In total, this population consisted of 2 269 students who were for the most part born in 1967.

Data was collected via questionnaire, which was completed by students during one school period in each school. 2 194 students participated in the survey which corresponds to 97 % of the target population. Most of those who did not participate were absent from school on the day of survey administration. There were only few who refused participation. 

The average age of the participants was 15.9 years and standard deviation was 0.3 years. 

The data collected through the school survey in 1983 formed the baseline data and the participating students subsequently formed the study cohort, which has been invited to participate in the follow-up postal surveys.

The study cohort had additionally participated in a narrower health-related school survey conducted when the students were in 8th grade in the fall of 1981 and the spring of 1982. However, only those who participated in the larger-scale survey in the spring of 1983 were included in the follow-up surveys. 

Data from the 1981 and 1982 surveys are described in more detail in Hillevi Aro’s dissertation (1988). 
Hillevi Aro’s dissertation (1988) 

1989, 1999, 2009 and 2019 — Follow-up studies

Follow-up studies have been carried out by mail-survey. The first follow-up survey was administered in 1989, when the participants were 22 years old. Of 2 139 young adults for whom an address was available, 1 656, or 76 % of the base-line participants, responded to the survey.

The next data collection phase took place in the spring of 1999, when the participants were 32 years old. Of the 2 091 participants for whom an address was available, 1 471, or 67 % of baseline participants, took part in the survey. 

At 42 years old, participants were once again invited to take part in the study by survey in the year 2009. An address was available for 2 117 participants and 1 334 of them responded to the survey. This constituted 61 % of the baseline participants. 

The follow-up study continued in the spring of 2019, when participants were 52 years old. An address was acquired for 2 059 participants and 1 160, or 53 % of baseline participants, took part in the survey.

TAM data is described in more detail in the Data resources catalog; however, not all data descriptions are available in English.
Data resources catalog

Response rates

Response Despite survey response rates slightly declining over the years, overall responsivity has remained quite good. Of those who 2 194 participants who responded to the school survey in 1983, 89 percent have participated in at least one of the follow-up surveys. Only 11 percent have been nonrespondent to all follow-up surveys and 36 percent have participated in all four follow-ups. 

On average, participants have responded to three of four follow-up surveys, which when considered along with baseline participation, means four survey responses from each participant. Data collection and study participation are further illustrated in Figure 1.   

Deceased participants numbered 85 (3,9 %) by the 2019 data collection period. Mortality within the study cohort has been studied in more detail in Berg et al.’s (2011) article, for which TAM data was linked to cause-of-death data obtained from Statistics Finland in the spring of 2010.
Berg et al (2010) (In Finnish)

Lähteet

Aro H. Stress, development and psychosomatic symptoms in adolescence. Academic dissertation. Acta Universitatis Tamperensis ser A vol 242. Tampere 1988, 134p.

Berg N, Huurre T, Kiviruusu O, Aro H. Nuoruusiän huono-osaisuus ja sen kasautumisen yhteys kuolleisuuteen. Sos Lääket Aikak 2011;48:168-181. (In Finnish)