From the information provided by the respondents on their principal activity in each month of the 48-month observation period, four mutually-exclusive activity states are defined using: in work, in education, in unemployment (‘NEET unemployed’), and inactive out of education (‘NEET inactive’). Young people who combine education and work are treated as ‘in education’, vocational training can unfortunately not be identified as separate from education. An individual’s chain of 48 monthly activity states from the age of 16 to 20 is interpreted as her school-to-work trajectory. The three panels are merged for the OECD countries to give the sample used for analysis.