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Statistical procedures for missing data have vastly improved, yet misconception and unsound practice still abound. The authors frame the missing-data problem, review methods, offer advice, and raise issues that remain unresolved. They clear up common misunderstandings regarding the missing at random (MAR) concept. They summarize the evidence against older(More)
This review presents a practical summary of the missing data literature, including a sketch of missing data theory and descriptions of normal-model multiple imputation (MI) and maximum likelihood methods. Practical missing data analysis issues are discussed, most notably the inclusion of auxiliary variables for improving power and reducing bias. Solutions(More)
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(More)
BACKGROUND The present study addresses diffusion of a psychosocial-based substance abuse prevention program, including: (a) teacher adoption, implementation, and maintenance; (b) teacher characteristics associated with implementation; (c) the relationship between integrity of program delivery and program outcomes; and (d) the effectiveness of teacher(More)
BACKGROUND Two strategies for preventing the onset of alcohol abuse, and marijuana and cigarette use were tested in junior high schools in Los Angeles and Orange Counties, California. The first strategy taught skills to refuse substance use offers. The second strategy corrected erroneous normative perceptions about prevalence and acceptability of use among(More)
OBJECTIVE This study examines whether the age of initiation of alcohol use mediates the effects of other variables that predict alcohol misuse among adolescents and also whether the age of initiation of alcohol use accounts for known gender differences in the severity of alcohol misuse. METHOD Data were taken from an ethnically diverse sample of 808 (412(More)
Social influence is central to models of adolescent substance use. Nonetheless, researchers fail to delineate the various forms of social influence. A framework that distinguishes between active (explicit drug offers) and passive (social modeling and overestimation of friends' use) social pressure was tested. The effect of these processes on alcohol and(More)
Outcome research has shown that drug prevention programs based on theories of social influence often prevent the onset of adolescent drug use. However, little is known empirically about the processes through which they have their effects. The purpose of the present study was to evaluate intervening mechanism theories of two program models for preventing the(More)
The authors describe 2 efficiency (planned missing data) designs for measurement: the 3-form design and the 2-method measurement design. The 3-form design, a kind of matrix sampling, allows researchers to leverage limited resources to collect data for 33% more survey questions than can be answered by any 1 respondent. Power tables for estimating correlation(More)
Sexual behavior and substance use represent major threats to the health and well-being of South African adolescents, especially in light of the high prevalence of HIV infection in this population. However, there is currently a lack of evidence-based school programs designed to address health risk behaviors. The current study details the evaluation of(More)