CHiSP is a longitudinal study initiated in 1969/70, including over 3,200 former high school students aged 15 to 16, along with their parents and teachers, tracking their biographies and attitudes through four re-surveys. The four follow-up surveys were conducted in 1985 when the sample were 30 years old, in 1997 when they were 43 years old, in 2010 at 56 years old, and finally, 2019/20 when the participants were 65 years old. The gender distributions remained similar throughout all phases, with males consistently accounting for around 47% of the sample.