The Role of Age, Period, and Cohort Effects on Smoking among the Students of Tehran University of Medical Science

Abstract

The aim of the study is to determine age, period, and cohort effects on trends in student’s cigarette smoking in Tehran University of medical science from 2006 to 2009. We analyzed data from subjects aged 18 to 23 years from Aids Researches Center with Cooperation Environment Researches Center and Accessory collegian. Intrinsic Estimator was used for analysis, that is a new method for resolving linear dependency between age, period, and cohort in linear regression models. In the present study, age effects exhibited increased for both sexes. Also, aging proportion of smoking increased. For both sexes log coefficients were negative at young ages. Period effects for females showed declines but for males there was no significant difference. Cohort effects for females were small and gradual declines were shown for male cohorts. Proportion of smoking at young cohorts was less than old cohorts and log coefficients were negative.There was an increasing trend on age effect .Although a reduction period effect was observed from 2006 to 2009 in females that can be due to utilizing smoking policies in previous years but such a trend was not showed for males. Cohort effect was observed for males and smoking proportion at young cohorts was less than old cohorts.