Tamika D. Gilreath

How Many Imputations are Really Needed? Some Practical Clarifications of Multiple Imputation Theory

Multiple imputation (MI) and full information maximum likelihood (FIML) are the two most common approaches to missing data analysis. In theory, MI and FIML are equivalent when identical models are tested using the same variables, and when m, the number of imputations performed with MI, approaches infinity. However, it is important to know how many imputations are necessary before MI and FIML are sufficiently equivalent in ways that are important to prevention scientists. MI theory suggests that small values of m, even on the order of three to five imputations, yield excellent results. Previous guidelines for sufficient m are based on relative efficiency, which involves the fraction of missing information (γ) for the parameter being estimated, and m. In the present study, we used a Monte Carlo simulation to test MI models across several scenarios in which γ and m were varied. Standard errors and p-values for the regression coefficient of interest varied as a function of m, but not at the same rate as relative efficiency. Most importantly, statistical power for small effect sizes diminished as m became smaller, and the rate of this power falloff was much greater than predicted by changes in relative efficiency. Based our findings, we recommend that researchers using MI should perform many more imputations than previously considered sufficient. These recommendations are based on γ, and take into consideration one’s tolerance for a preventable power falloff (compared to FIML) due to using too few imputations.

Psychosocial Factors Associated With Adolescent Electronic Cigarette and Cigarette Use

BACKGROUND: Use of electronic cigarettes (e-cigarettes) among adolescents has increased since their introduction into the US market in 2007. Little is known about the role of e-cigarette psychosocial factors on risk of e-cigarette or cigarette use in adolescence. METHODS: Information on e-cigarette and cigarette psychosocial factors (use and attitudes about use in the home and among friends) was collected from 11th- and 12th-grade participants in the Southern California Children’s Health Study during the spring of 2014. RESULTS: Of 2084 participants, 499 (24.0%) had used an e-cigarette, including 200 (9.6%) current users (past 30 days); 390 participants (18.7%) had smoked a combustible cigarette, and 119 (5.7%) were current cigarette smokers. Cigarette and e-cigarette use were correlated. Nevertheless, 40.5% (n = 81) of current e-cigarette users had never smoked a cigarette. Psychosocial factors (home use of each product, friends’ use of and positive attitudes toward e-cigarettes and cigarettes) and participant perception of the harm of e-cigarettes were strongly positively associated both with e-cigarette and cigarette use. Most youth who reported e-cigarette use had friends who used e-cigarettes, and almost half of current users reported that they did not believe there were health risks associated with e-cigarette use. CONCLUSIONS: Longitudinal studies of adolescents are needed to determine whether the strong association of e-cigarette psychosocial factors with both e-cigarette and cigarette use will lead to increased cigarette use or dual use of cigarettes and e-cigarettes, or whether e-cigarettes will serve as a gateway to cigarette use.

Social-Ecological Influences on Patterns of Substance Use Among Non-Metropolitan High School Students

Patterns of substance use are examined in a sample of over 1,200 youth in a non-metropolitan region of New England. Self-reported history and frequency of alcohol, tobacco, marijuana, inhalants, pain medications, and other hard drug use was assessed for 9th and 10th grade students. Latent class analyses identified four patterns of substance use: non-users (22%), alcohol experimenters (38%), occasional polysubstance users (29%), and frequent polysubstance users (10%). Contextual risk and protective factors in the individual, family, peer, and community domains predicted substance use patterns. Youth report of peer substance use had the largest effects on substance use class membership. Other individual characteristics (e.g., gender, antisocial behavior, academic performance, perceived harm from use), family characteristics (e.g., parental drinking, parental disapproval of youth use), and community characteristics (e.g., availability of substances) demonstrated consistent effects on substance use classes. Implications for prevention are discussed from a social-ecological perspective.

Past 15-year trends in adolescent marijuana use: Differences by race/ethnicity and sex

BACKGROUND The potential for increases in adolescent marijuana use is an important concern given recent changes in marijuana policy. The purpose of this study was to estimate trends in marijuana use from 1999 to 2013 among a national sample of US high school students. We examine changes over time by race/ethnicity and sex. METHODS Data are from the National Youth Risk Behavior Survey (YRBS), which involves biennial, school-based surveys that generate nationally representative data about 9th-12th grade students in the United States. Students self-reported sex, race/ethnicity, and marijuana use (i.e., lifetime use, past 30-day use, any use before age 13). We generated national estimates of the prevalence of marijuana use for the time period, and also tested for linear and quadratic trends (n=115,379). RESULTS The prevalence of lifetime marijuana use decreased modestly from 1999 to 2009 (44% to 37%), and has increased slightly since 2009 (41%). Other marijuana use variables (e.g., past 30-day use) followed a similar pattern over time. The prevalence of past 30-day use from 1999 to 2013 for all groups and both sexes was 22.5%, and it was lowest among Asians and highest among American Indian/Alaska Natives. Although boys have historically had a higher prevalence of marijuana use, results indicate that male-female differences in marijuana use decreased over time. CONCLUSION Despite considerable changes in state marijuana policies over the past 15 years, marijuana use among high school students has largely declined. Continued surveillance is needed to assess the impact of policy changes on adolescent marijuana use.

Substance Use Among Military-Connected Youth The California Healthy Kids Survey

BACKGROUND Young people in military-connected families may be exposed to deleterious stressors, related to family member deployment, that have been associated with externalizing behaviors such as substance use. Substance use predisposes youth to myriad health and social problems across the life span. PURPOSE This study examined the prevalence and correlates of lifetime and recent substance use in a normative sample of youth who were either connected or not connected to the military. METHODS Data are from a subsample of the 2011 California Healthy Kids Survey (N=14,149). Items in the present analyses included present familial military affiliation (no one, parent, sibling); number of deployments (none, one, two or more); gender; grade; and race/ethnicity. Substance use items assessed whether the youth reported lifetime use of alcohol, tobacco, marijuana, other drugs, or prescription drugs; and recent (past 30 days) use of alcohol, tobacco, marijuana, and other drugs. RESULTS Multivariate analysis conducted in 2012 revealed that an increase in the number of deployments was associated with a higher likelihood of lifetime and recent use, with the exception of lifetime smoking. CONCLUSIONS These results indicate that experiences associated with deployment of a family member may increase the likelihood of substance use.

Well-being and suicidal ideation of secondary school students from military families.

BACKGROUND The mental health of children is a primary public health concern; adolescents of military personnel may be at increased risk of experiencing poorer well-being overall and depressive symptoms specifically. These adolescents experience individual and intrafamilial stressors of parental deployment and reintegration, which are directly and indirectly associated with internalizing behaviors. PURPOSE The present study sought to better understand the influence of parental military connectedness and parental deployment on adolescent mental health. METHODS Data from the 2011 California Healthy Kids Survey examined feeling sad or hopeless, suicidal ideation, well-being, and depressive symptoms by military connectedness in a subsample (n = 14,299) of seventh-, ninth-, and 11th-grade California adolescents. Cross-classification tables and multiple logistic regression analyses were used. RESULTS More than 13% of the sample had a parent or sibling in the military. Those with military connections were more likely to report depressive symptoms and suicidal ideation. Controlling for grade, gender, and race/ethnicity, reporting any familial deployment compared with no deployments was associated with increasing odds of experiencing sadness or hopelessness, depressive symptoms, and suicidal ideation. CONCLUSIONS Findings emphasize the increased risk of mental health issues among youth with parents (and siblings) in the military. Although deployment-related mental health stressors are less likely during peace, during times of war there is a need for increased screening in primary care and school settings. Systematic referral systems and collaboration with community-based mental health centers will bolster screening and services.

Patterns of Alternative Tobacco Product Use: Emergence of Hookah and E-cigarettes as Preferred Products Amongst Youth

PURPOSE There is a growing public health concern related to the rapid increase in the use of multiple tobacco products among adolescents. This study examined patterns of adolescent use of cigarettes, e-cigarettes, cigars/cigarillo, hookah/waterpipe, and smokeless/dip/chewing tobacco in a population of southern California adolescents. METHODS Data from 2,097 11th- and 12th-grade participants in the Southern California Childrens Health Study were collected via self-report in 2014. Study participants were asked about lifetime and current (past 30 days) use of cigarettes, cigars/cigarillos/little cigars, e-cigarettes, hookah/waterpipe, and smokeless/dip/chewing tobacco. Latent class analysis (LCA) was used to identify patterns of tobacco use. RESULTS Hookah/waterpipe tobacco use had the highest current prevalence (10.7%) followed by e-cigarettes (9.6%). The prevalence of use of smokeless/dip/chewing tobacco was lowest, with 2.2% of adolescents reporting current use. The LCA suggested four distinct classes, comprising nonusers (72.3% of the sample), polytobacco experimenters (13.9%), e-cigarette/hookah users (8.2%), and polytobacco users (5.6%). Multinomial logistic regression based on these four classes found that males had double the odds to be polytobacco users relative to nonusers compared to females (odds ratio, 2.3; 95% confidence interval, 1.26-4.25). CONCLUSIONS By identifying naturally occurring configurations of tobacco product use in teens, these findings may be useful to practitioners and policymakers to identify the need for tobacco control interventions that address specific tobacco products and particular combinations of polytobacco use. LCA can be used to identify segments of the population overrepresented among certain tobacco use classes (e.g., boys) that may benefit most from targeted polyproduct intervention approaches.

The Promotional Role of School and Community Contexts for Military Students

This article examines how supportive public school environments can serve as a promotional context for the development of children and adolescents from military families. The authors integrate theory and research from multiple research strands (e.g., human development, studies of at-risk youth, educational reform, goodness of fit theory, and school climate) to outline how public schools can support the development of all children and adolescents. This article provides further support for the supposition that school climates and the social-ecological contexts surrounding a school (e.g., universities, communities, school districts) have the potential to protect at-risk children and adolescents from an array of negative social, emotional, and psychological outcomes. The authors draw linkages between these research domains and the development of military children and adolescents. Promotional civilian school environments embedded within supportive and inclusive contexts can create a social infrastructure that supports the development of military children and adolescents. The authors argue that this conceptual approach can create a foundation for interventions and research that focuses on schools as normative supportive developmental settings for military children and youth during challenging times of war (e.g., deployments and multiple school transitions). This article concludes with a discussion of future directions in research on the development of military children and adolescents. Based on a heuristic conceptual model that outlines areas needing further research, the authors call for a deeper theoretical and empirical integration of school climate and external contextual factors surrounding the school. Investigating the social and organizational dynamics within these contexts can result in a more comprehensive picture of the development of military children and adolescents.

Prevalence and correlates of victimization and weapon carrying among military- and nonmilitary-connected youth in Southern California.

OBJECTIVES The present analysis sought to explore the normative rates and correlates of school victimization and weapon carrying among military-connected and nonmilitary-connected youth in public schools in Southern California. METHODS Data are from a sub-sample of the 2011 California Healthy Kids Survey (N=14,512). Items to assess victimization and weapon carrying were separated into three categories: physical acts (e.g., being pushed or shoved), nonphysical acts (e.g., having rumors spread about them) and weapon carrying. RESULTS The bivariate results indicate that youth with a military-connected parent had higher rates of physical victimization (56.8%), nonphysical victimization (68.1%), and weapon carrying (14.4%) compared to those with siblings serving (55.2%, 65.2%, and 11.4%, respectively) and nonmilitary-connected (50.3%, 61.6%, and 8.9%, respectively) youth. Having a parent in the military increased the odds of weapon carrying by 29% (Odds Ratio=1.29, 95% confidence interval=1.02-1.65). Changing schools and a larger number of family member deployments in the past 10years were associated with significant increases in the likelihood of victimization and weapon carrying. CONCLUSIONS The results of this analysis warrant a focus on school supports for youth experiencing parental military service, multiple relocations and deployments of a family member.

E-cigarettes, Cigarettes, and the Prevalence of Adolescent Tobacco Use

BACKGROUND: Adolescent e-cigarette use has increased rapidly in recent years, but it is unclear whether e-cigarettes are merely substituting for cigarettes or whether e-cigarettes are being used by those who would not otherwise have smoked. To understand the role of e-cigarettes in overall tobacco product use, we examine prevalence rates from Southern California adolescents over 2 decades. METHODS: The Children’s Health Study is a longitudinal study of cohorts reaching 12th grade in 1995, 1998, 2001, 2004, and 2014. Cohorts were enrolled from entire classrooms in schools in selected communities and followed prospectively through completion of secondary school. Analyses used data from grades 11 and 12 of each cohort (N = 5490). RESULTS: Among 12th-grade students, the combined adjusted prevalence of current cigarette or e-cigarette use in 2014 was 13.7%. This was substantially greater than the 9.0% adjusted prevalence of current cigarette use in 2004, before e-cigarettes were available (P = .003) and only slightly less than the 14.7% adjusted prevalence of smoking in 2001 (P = .54). Similar patterns were observed for prevalence rates in 11th grade, for rates of ever use, and among both male and female adolescents and both Hispanic and Non-Hispanic White adolescents. CONCLUSIONS: Smoking prevalence among Southern California adolescents has declined over 2 decades, but the high prevalence of combined e-cigarette or cigarette use in 2014, compared with historical Southern California smoking prevalence, suggests that e-cigarettes are not merely substituting for cigarettes and indicates that e-cigarette use is occurring in adolescents who would not otherwise have used tobacco products.