Ključne besede: dejavniki kajenja, romunski mladostniki, preprečevanje kajenja stronger intention to smoke in the future will predict smoking onset. Second, we compare the outcomes and amount of variance explained when using a crosssectional compared to a longitudinal design.
METHODS
Sample and procedureIn spring 2004, five senior high schools from ClujNapoca, a city in north-west Romania with approximately 330,000 inhabitants and 39 high schools, were randomly chosen and approached to participate in a survey about adolescent smoking behaviour. Time and financial constraints limited the inclusion of more schools in the study. The principals of the five schools were informed about the survey during individual meetings with the research team; all principals agreed to participate, and all first-year classes from the five schools were involved in the survey. Consent was obtained from the school administration only, in line with standard procedure in Romania. Data were gathered in two waves. A baseline measurement was conducted in May-June 2004 (T1) among students from 19 first-year senior high school classes (aged 15 to 17), and a follow-up measurement was performed 12 months later (T2). The students were not informed in advance about the date on which the assessment would take place. The research team administered the questionnaires to each class; classroom completion of the questionnaire took approximately 50 minutes. Students were asked to read an introductory letter. They were assured that the researchers would treat their questionnaires confidentially and that they could refuse to participate by leaving the questionnaire blank. They put their completed questionnaires in an envelope, sealed it and wrote their names on the envelope and then the researchers collected the envelopes. No refusals were recorded; non-participation was exclusively due to absence of students on the day of assessment. The questionnaires were filled in by 473 students at T1 and 482 students at T2. A total of 416 students participated in both measurements; 66.5% of these were girls.