Background: The key objective of this primary prevention programme evaluation project is to compare the differences between the results of an intervention featuring a community-based primary prevention programme and the application of a so-called minimum prevention programme. The project is designed as a quasi-experimental five-year study without any randomisation in the se lection of participants. In the qualitative part, the investigators have sought to obtain more information on the ways in which both programmes under comparison are implemented and to compare such information with official documents pertaining to both types of programmes in order to acquire an independent source of qualitative data on the underlying features and the nature of the preventive interventions performed and compared as part of the research study. In addition, qualitative data are used to support the development of the interpretation basis for the results of the quasi-experiment in an effort to capitalise on the advantages ensuing from the matching of both quantitative and qualitative data. Methods: Sampling for the qualitative part was carried out using the Total Sample method – all the prevention methodologists in the schools under study, included both in the experimental and control groups, were nominated. Finally, out of a population comprising 25 methodologists, 19 methodologists took part in the study. Despite the investigators’ efforts, it was not possible to conduct interviews with the remaining methodologists. The principal method used to collect data was a semi-structured interview whose main items were based on the content analysis of documentation pertaining to both types of programmes. Results: As expected, the results showed significant differences in the standards of implementation of individual programmes, particularly as far as the control group was concerned. In contrast, they showed a considerable degree of consistency in the concept and application of the community-based prevention programme, which, in the former case, is associated with the incoherent system of training for prevention methodologists, gaps in the harmonisation of the minimum prevention programme methodology, and the ambiguity of the documents covering this prevention approach, which provide grounds for a wide range of interpretations, thus impeding any more rigorous evaluation. On the contrary, in the latter case, the result is obviously influenced by the fact that the programme is coordinated and managed by a single organisation which is, moreover, responsible for an integrated system of training for all the groups involved and strictly enforces compliance with all the programme implementation rules.

Key words: evaluation – primary prevention – risky behaviour – minimum prevention programme – school prevention methodologist