Following recruitment, parents and adolescents completed self-administered questionnaires on an annual basis. These were completed in a private setting, such as their homes, at an office, or an another convenient location. The questionnaires included extensive questions about stressful life events, depressive symptoms,and substance use using validated scales from previous research studies-. The sample included members of several birth cohorts in an accelerated longitudinal design , thus it was useful for testing the association between marijuana use and depressive symptoms among adolescents and young adults from ages 11 to 23. This is an important period of the life course when substance use increases and decreases among many young people .The sample members were mostly Caucasian , with the rest African-American or members of other racial/ethnic groups . About halfwere females . The average age during year one was 12.8 and 20.1 during year eight.
The average annual family income was close to $55,000. Comparisons with U.S. Census Bureau data demonstrated that the FWHS sample was representative of the demographic distribution of the population in the local metropolitan area in terms of race, family income, parental education, family size, and family structure. The Institutional Review Boards of the university that sponsored this research and of the local health centers from which the respondents were recruited approved this study as satisfying human subjects protections. A measure of stressful events was needed to assess hypothesis 4. Researchers have classified stressful events as controllable or uncontrollable, which depends on the volition of the individual. Since depressive symptoms or marijuana use may lead to controllable events, such as poor relations or school problems,thus potentially confounding their causal association, and recent research indicates that uncontrollable experiences are the principal determinant of mental health problems , this study focused on largely uncontrollable events.
These included past-year experiences such as parental mental health problems;parental divorce or separation; family financial problems; death, illness, or accidents among family or friends; and changes in school or residence. The events were measured each year by a checklist of 16 items derived from the Junior High Life Experiences Survey and the Family Inventory of Life Events and Life Changes.Studies have demonstrated that several variables affect the associations among marijuana use, depressive symptoms, and stressful life events. For example, research suggests that self-esteem, self-efficacy, and positive family relationships attenuate the effects of stressful events on marijuana use or depressive symptoms . Therefore, measures of each of these, along with peer substance use, a common predictor of marijuana use , and several demographic covariates were included in the models.Self-efficacy was measured during each year by Pearlin and Schooler’s mastery scale. This consisted of seven questions about perceived personal control over one’s environment; in particular, a sense of helplessness, fatalism, and a lack of problem-solving ability.
Since there was variation in the response patterns a cross years, each observed variable was standardized within year prior to creating additive scales. The standardization process consisted of taking the z-scores of each variable in each year. The z -scores were then added together to create the self-efficacy scale. Higher scores on this scale indicated greater perceived control over life. The alpha coefficients for the annual scales ranged from 0.87 – 0.92.Self-esteem was gauged annually with Rosenberg’s10-item scale. The questions inquired about respondents’ feelings of worth, pride, ability, respect,and satisfaction with life. Higher values indicated higher self-esteem. Since there was variation in the response patterns of the self-esteem items across years, each was standardized within year prior to creating additive scales. The standardization process consisted of taking the z -scores of each variable in each year.The z-scores were then summed to create the self-esteem scale .The alpha coefficients ranged from 0.82 – 0.88.Family relations were measured each year with 15 questions from the Family Adaptation and Cohesion Scale,which asked about family closeness,support, joint activities, and problem solving.Each constituent variable was standardized within year prior to creating additive scales. The z-scores were then added together to create the family relations scale . Higher scores on this scale specified better family relations. The alpha coefficients ranged from 0.80 – 0.92.Peer substance use was based on a set of questions that asked how often the respondents’ three closest friends engaged in the following types of substance use in the previous year: alcohol, cigarettes, marijuana, and other types of illicit substance use. Responses to each question ranged from zero times to 31 or more times .