Absenteeism in Northern Ireland schools has been halved since the introduction of the province's common curriculum, according to new research.
But within the overall reduction is a hard core of unauthorised absence, where pupils are often missing with parental connivance.
The findings come in the third province-wide survey into the problem, in which education welfare officers visited all 900 secondary schools and a sample of 200 primaries, recording pupils absent for a total of 14 days or more in a 12-week period.
The total for absenteeism across the compulsory school-age range was 3 per cent, in contrast to the last survey - in 1982 - of 6.1 per cent, which applied to all age groups.
Education minister Michael Ancram welcomed the reduction, and said he hoped for further improvements as schools developed greater emphasis on vocational studies.
Within the total, however, some 52 per cent of persistent absentees - more than 4,000 pupils, had seven or more days off for reasons other than illness. The officers believe that in a great majority of cases parents were well aware their children were not at school. Some had been kept at home to work on farms, or do part-time jobs, or to look after siblings as well as take family holidays.
The figures for absentees included 60 per cent entitled to free meals and 23 per cent who had received help with learning difficulties, indicating the links between truancy and social disadvantage. Seventy per cent of persistent truants are expected to be early leavers.
The report, by Anne E Sutherland, is available from the Northern Ireland Council for Educational Research Unit, Queen's University, Belfast.