Arielle S. Selya

A Practical Guide to Calculating Cohen’s f2, a Measure of Local Effect Size, from PROC MIXED

Reporting effect sizes in scientific articles is increasingly widespread and encouraged by journals; however, choosing an effect size for analyses such as mixed-effects regression modeling and hierarchical linear modeling can be difficult. One relatively uncommon, but very informative, standardized measure of effect size is Cohen’s f2, which allows an evaluation of local effect size, i.e., one variable’s effect size within the context of a multivariate regression model. Unfortunately, this measure is often not readily accessible from commonly used software for repeated-measures or hierarchical data analysis. In this guide, we illustrate how to extract Cohen’s f2 for two variables within a mixed-effects regression model using PROC MIXED in SAS® software. Two examples of calculating Cohen’s f2 for different research questions are shown, using data from a longitudinal cohort study of smoking development in adolescents. This tutorial is designed to facilitate the calculation and reporting of effect sizes for single variables within mixed-effects multiple regression models, and is relevant for analyses of repeated-measures or hierarchical/multilevel data that are common in experimental psychology, observational research, and clinical or intervention studies.

Risk factors for adolescent smoking: Parental smoking and the mediating role of nicotine dependence

BACKGROUND Parental smoking and early-emerging nicotine dependence symptoms are well-documented risk factors for adolescent smoking. However, very little is known about the mediating pathways through which these risk factors may act, or whether parental smoking may cause or signal early-emerging nicotine dependence symptoms. METHODS Data were drawn from the longitudinal Social and Emotional Contexts of Adolescent Smoking Patterns Study. Adolescents who had smoked under 100 cigarettes in their lifetime (n=594; low-exposure group) and adolescents who had smoked over 100 cigarettes, but fewer than 5 cigarettes per day (n=152) were included in the analyses. Path analysis was performed on longitudinal data to investigate the association between parental smoking and smoking frequency at the 48 months follow-up, both directly and through mediating variables of smoking frequency, smoking quantity, and nicotine dependence. RESULTS Fathers smoking was associated with higher adolescent nicotine dependence scores at the baseline assessment wave. Structural equation modeling revealed that mothers smoking at baseline was associated with adolescents smoking frequency at the 48-month follow-up, and its effect was partially mediated by both smoking frequency and nicotine dependence among low-exposure adolescent smokers. CONCLUSIONS Parental smoking is a risk factor for future smoking in low-exposure adolescent smokers, above and beyond the risks posed by smoking behavior and nicotine dependence. Moreover, parental smoking is associated with early-onset nicotine dependence in low-exposure adolescent smokers. As an easily measureable risk factor, parent smoking status can be used to identify and intervene with novice adolescent smokers who are at high risk for chronic smoking behavior.

Depression and nicotine dependence from adolescence to young adulthood

INTRODUCTION Despite the highly replicated relationship between depression and nicotine dependence, little is known about this association across both time and levels of lifetime smoking exposure. In the present study, we evaluate if symptoms of depression are associated with emerging nicotine dependence after accounting for smoking exposure and whether this relationship varies from adolescence to young adulthood and across increasing levels of smoking. PATIENTS AND METHODS The sample was drawn from the Social and Emotional Contexts of Adolescent Smoking Patterns Study which measured smoking, nicotine dependence and depression over 6 assessment waves spanning 6years. Analyses were based on repeated assessment of 941 participants reporting any smoking 30days prior to individual assessment waves. Mixed-effects regression models were estimated to examine potential time and smoking exposure varying effects in the association between depression and nicotine dependence. RESULTS Inter-individual differences in mean levels of depression and within subject changes in depression from adolescence to young adulthood were each significantly associated with nicotine dependence symptoms over and above lifetime smoking exposure. This association was consistent across both time and increasing levels of lifetime smoking. DISCUSSION Depression is a consistent risk factor for nicotine dependence over and above exposure to cigarettes and this association can be demonstrated from the earliest experiences with smoking in adolescents through the establishment of more regular smoking patterns across the transition to young adulthood. CONCLUSION Depression remains a prominent risk factor for nicotine dependence, and youth with depression symptoms represent an important subgroup in need of targeted smoking intervention.

Early emerging nicotine dependence symptoms in adolescence predict daily smoking in young adulthood

PURPOSE The present study evaluated the predictive validity of individual early emerging nicotine dependence symptoms in adolescence on smoking behavior in young adulthood. METHODS A total of 492 adolescents who, at baseline, had not smoked more than 100 cigarettes in their lifetime and 123 adolescents who smoked more than 100 cigarettes lifetime, and who participated in the 6-year follow-up assessment were included in the present analyses. Predictive validity of 10 nicotine dependence items administered at baseline was evaluated at the 6 year follow-up when the sample had entered young adulthood (mean age=21.6). RESULTS Among adolescents who had smoked fewer than 100 cigarettes, experiencing higher levels of overall nicotine dependence as well as individual symptoms at baseline longitudinally predicted an increase in risk for daily smoking in young adulthood, after controlling for baseline smoking and other tobacco use. For adolescents who had smoked more than 100 cigarettes at baseline, level of nicotine dependence and individual symptom endorsement did not predict smoking behavior in young adulthood. CONCLUSIONS These findings add to accumulating evidence that early emerging dependence symptoms reported at low levels of smoking exposure signal a greater propensity for continued smoking behavior. Screening for these early emerging symptoms among novice adolescent smokers represents an important and unused tool in tobacco control efforts aimed at preventing the development of chronic smoking patterns.

Time-varying effects of smoking quantity and nicotine dependence on adolescent smoking regularity

BACKGROUND Little is known about time-varying effects of smoking quantity and nicotine dependence on the regularity of adolescent smoking behavior. METHODS The sample was drawn from the Social and Emotional Contexts of Adolescent Smoking Patterns Study which followed adolescent smokers over 5 assessment waves spanning 48 months. Participants included former experimenters (smoked <100 cigarettes/lifetime but did not smoke in past 90 days), recent experimenters (smoked <100 cigarettes/lifetime and smoked in past 90 days), and current smokers (smoked >100 cigarettes/lifetime and smoked in past 30 days). Mixed-effects regression models were run to examine the time-varying effects of smoking quantity and nicotine dependence on regularity of smoking behavior, as measured by number of days smoked. RESULTS Smoking quantity and nicotine dependence were each found to be significantly associated with regularity of adolescent smoking and the size of each effect exhibited significant variation over time. The effect of smoking quantity decreased across time for each smoking group, while the effect of nicotine dependence increased across time for former and recent experimenters. By the 48-month follow-up, the effects of smoking quantity and nicotine dependence had each stabilized across groups. CONCLUSIONS This study reveals that smoking quantity and nicotine dependence are not static risk factors for the development of more regular smoking patterns. At low levels of smoking when nicotine dependence symptoms are less common, smoking quantity is a stronger predictor of increased regularity of smoking, while for more experienced smokers, nicotine dependence predicts further increases in regularity.

Alcohol problems as a signal for sensitivity to nicotine dependence and future smoking.

BACKGROUND Alcohol use is a well-documented risk factor for the emergence of chronic smoking behavior. Very little is known, however, about the mediating pathways through which alcohol and/or alcohol-related problems influence future smoking. METHODS Data were drawn from the longitudinal Social and Emotional Contexts of Adolescent Smoking Patterns Study (SECASPS). Adolescents who had smoked under 100 cigarettes in their lifetime (n=898; experimenters) and adolescents who had smoked over 100 cigarettes, but fewer than 5 cigarettes per day (n=152: current smokers) were examined separately (grouping variable). Path analysis was performed to investigate the association between alcohol related problems at baseline (primary predictor) and smoking regularity at the 48 month follow-up (primary outcome), both directly and through mediating variables of smoking quantity and frequency, and nicotine dependence (averaged across these measures at 6-, 15-, and 24-month assessment waves). RESULTS Among experimenters, after controlling for smoking and alcohol use, the association between alcohol-related problems at baseline and smoking frequency 48 months later was fully mediated by nicotine dependence symptoms. Among current smokers, only past smoking behavior was associated with 48-month smoking frequency. CONCLUSIONS Alcohol-related problems are a risk factor for future smoking among novice adolescent smokers above and beyond drinking or smoking per se. By signaling sensitivity to nicotine dependence symptoms, alcohol related problems represent an easily measureable risk factor that can be used to identify and intervene with adolescents before more chronic smoking behaviors emerge.

Adolescent Nicotine Dependence Symptom Profiles and Risk for Future Daily Smoking

Recent research on adolescent smokers suggests that there are important differences in the types of nicotine dependence (ND) symptoms that emerge and different patterns of ND symptoms. The purpose of this study was to use data from the longitudinal Social and Emotional Contexts of Adolescent Smoking Patterns Study to identify latent subgroups of adolescent experimental and nondaily smokers varying in number and types of endorsed ND symptoms. Profiles were identified using baseline level of smoking, individual patterns of ND symptoms and other ND risk factors. Discrete time survival analysis was used to examine profile differences in probability of becoming daily smokers 48 months later. Four distinct subgroups of smokers with different patterns of smoking behavior, ND symptoms, and alcohol and other substance use emerged. Heavier smoking adolescents with high symptom endorsement, particularly the need to smoke in the morning, were most likely to become daily smokers 48 months later. A subgroup of social smokers had high smoking exposure and symptom endorsement (except need to smoke in the morning), and high levels of other substance use. Despite lower rates of smoking frequency and quantity compared to the heavier smoking class, 36% of these adolescents smoked daily by 48 months, with a steeper decline in survival rates compared to other lighter smoking classes. Morning smoking symptoms and symptoms prioritizing smoking (i.e., choosing to spend money on cigarettes instead of lunch or smoking when ill or where smoking is forbidden) might quickly identify adolescent non-daily smokers with more severe dependence and higher risk for daily smoking. A focus on skills for avoiding social situations involving use of alcohol and other drugs and reducing peer smoking influences may be an important focus for reducing smoking and other substance use among social smokers.

Coping with the 10th anniversary of 9/11: Muslim Americans' sadness, fear, and anger

The events of 9/11 marked an increase in prejudice, discrimination, and other forms of unfair treatment toward Muslim Americans. We present a study that examined the emotions of Muslim Americans in the days preceding the ten-year 9/11 anniversary. We measured the antecedents (concerns) and consequences (coping) of sadness, fear, and anger. The 9/11 anniversary precipitated intense concerns with loss and discrimination, and intense feelings of sadness, fear, and anger. We measured three coping responses: rumination, avoidance of public places, and religious coping. Participants engaged in all three coping responses, with seeking solace in ones religion being the most frequent response. Moreover, emotions mediated the relationship between concerns and coping responses. Sadness accounted for the association between concern with loss and rumination. Fear explained the association between concern with discrimination and avoidance. Anger accounted for the association between concern with discrimination and religious coping.

Post-traumatic Stress Disorder Symptoms Mediate the Relationship Between Trauma Exposure and Smoking Status in College Students

The present study examined the relationship between trauma exposure and smoking status and the extent to which post-traumatic stress disorder symptoms mediated this relationship in a sample of 329 college students who experienced a prior traumatic event. Participants experienced an average of 2.2 prior traumas, and approximately 15% (n = 49) were smokers. Bootstrapping analyses revealed that after controlling for age, gender and time since trauma, post-traumatic stress disorder symptoms served as a pathway through which trauma exposure increased the risk of smoking [BC 95% CI (0.02, 0.18)]. Results appeared to be due largely to the influence of hyperarousal symptoms [BC 95% CI (0.05, 0.22)]. Comprehensive interventions for undergraduate smokers may be improved by attending to the impact of prior trauma and mental health needs.

Exploring alternate processes contributing to the association between maternal smoking and the smoking behavior among young adult offspring

INTRODUCTION Maternal smoking during pregnancy (MSP) is a known risk factor for regular smoking in young adulthood and may pose a risk independently of mothers lifetime smoking. The processes through which MSP exerts this influence are unknown but may occur through greater smoking quantity and frequency following initiation early in adolescence or increased sensitivity to nicotine dependence (ND) at low levels of smoking. METHODS This study used path analysis to investigate adolescent smoking quantity, smoking frequency, and ND as potential simultaneous mediating pathways through which MSP and mothers lifetime smoking (whether she has ever smoked) increase the risk of smoking in young adulthood among experimenters (at baseline, <100 cigarettes/lifetime) and current smokers (>100 cigarettes/lifetime). RESULTS For experimenters, MSP was directly associated with more frequent young adult smoking and was not mediated by adolescent smoking behavior or ND. Independently of MSP, the effect of mothers lifetime smoking was fully mediated through frequent smoking and was heightened ND during adolescence. Controlling for MSP eliminated a previously observed direct association between mothers lifetime smoking and future smoking among experimenters. For current smokers, only prior smoking behavior was associated with future smoking frequency. CONCLUSIONS These results seem to rule out sensitivity to ND and increased smoking behavior as contributing pathways of MSP. Further, the impact of MSP on young adult smoking extends beyond that of having an ever-smoking mother. Future work should test other possible mediators; for example, MSP-related epigenetic changes or gene variants influencing the brains nicotine response.