No abstract

JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range of content in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new forms of scholarship. For more information about JSTOR, please contact support@jstor.org.. American Statistical Association is collaborating with JSTOR to digitize, preserve and extend access to Journal of the American Statistical Association.Classifying an observation into one of several populations is discriminant analysis, or classification. Relating qualitative variables to other variables through a logistic cdf functional form is logistic regression. Estimators generated for one of these problems are often used in the other. If the populations are normal with identical covariance matrices, discriminant analysis estimators are preferred to logistic regression estimators for the discriminant analysis problem. In most discriminant analysis applications, however, at least one variable is qualitative (ruling out multivariate normality). Under nonnormality, we prefer the logistic regression model with maximum likelihood estimators for solving both problems. In this article we summarize the related arguments, and report on our own supportive empirical studies.

Research on the effectiveness of school-based programs for preventing or reducing aggressive behavior was synthesized with a meta-analysis. Changes in aggressive behavior between pretest and posttest were analyzed for developmental patterns and characteristics associated with differential effects. Control groups showed little change in aggressive behavior, but there were significant reductions among intervention groups. Most studies were conducted on demonstration programs; the few studies of routine practice programs showed much smaller effects. Among demonstration programs, positive outcomes were associated with a variety of study, subject, and intervention characteristics. Most notably, higher risk youth showed greater reductions in aggressive behavior, poorly implemented programs produced smaller effects, and different types of programs were generally similar in their effectiveness, other things equal.

Schools seeking prevention programs may choose from a range of effective programs with some confidence that whatever they pick will be effective. Without the researcher involvement that characterizes the great majority of programs in this meta-analysis, schools might be well-advised to give priority to those that will be easiest to implement well in their settings.

Meta-analysis was used to synthesize research on the effects of outpatient treatment on substance use outcomes for adolescents with substance use disorders. An extensive literature search located 45 eligible experimental or quasi-experimental studies reporting 73 treatment-comparison group pairs, with many of the comparison groups also receiving some treatment. The first analysis examined 250 effect sizes for the substance use outcomes of adolescents receiving different types of treatment relative to the respective comparison groups. As a category, family therapy programs were found to be more effective than their comparison conditions, whereas no treatment programs were less effective. However, not all treatment types were compared with each other in the available research, making it difficult to assess the comparative effectiveness of the different treatments. To provide a more differentiated picture of the relative improvement in substance use outcomes for different treatments, a second analysis examined 311 pre-post effect sizes measuring changes in substance use for adolescents in the separate treatment and comparison arms of the studies. The adolescents in almost all types of treatment showed reductions in substance use. The greatest improvements were found for family therapy and mixed and group counseling. Longer treatment duration was associated with smaller improvements, but other treatment characteristics and participant characteristics had little relationship to the pre-post changes in substance use. Based on these findings family therapy is the treatment with the strongest evidence of comparative effectiveness, although most types of treatment appear to be beneficial in helping adolescents reduce their substance use.

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The Campbell Collaboration (C2) was founded on the principle that systematic reviews on the effects of interventions will inform and help improve policy and services. C2 offers editorial and methodological support to review authors throughout the process of producing a systematic review. A number of C2's editors, librarians, methodologists and external peerreviewers contribute. The Campbell Collaboration

(1) Summary Plant cell culture systems were initially explored for use in commercial synthesis of several high value secondary metabolites, allowing for sustainable production that was not limited by the low yields associated with natural harvest or the high cost associated with complex chemical synthesis. Although there have been some commercial successes, most notably paclitaxel production from Taxus sp., process limitations exist with regards to low product yields and inherent production variability. A variety of strategies are being developed to overcome these limitations including elicitation strategies, in situ product removal and metabolic engineering with single genes and transcription factors. Recently, the plant cell culture production platform has been extended to pharmaceutically active heterologous proteins. Plant systems are beneficial because they are able to produce complex proteins that are properly glycosylated, folded and assembled without the risk of contamination by toxins that are associated with mammalian or microbial production systems. Additionally, plant cell culture isolates transgenic material from the environment, allows for more controllable conditions over field grown crops and promotes secretion of proteins to the medium, reducing downstream purification costs. Despite these benefits, the increase in cost of heterologous protein synthesis in plant cell culture as opposed to field grown crops is significant and therefore processes must be optimized with regards to maximizing secretion and enhancing protein stability in the cell culture media. This review discusses recent advancements in plant cell culture processing technology, focusing on progress towards overcoming the problems associated with commercialization of these production systems and highlighting recent commercial successes.