The way in which intervention studies have "personality" and why it is important to meta-analysis.

Intervention studies represent webs of interrelated substantive and methodological characteristics that take on different patterns in different studies and different intervention areas. All too often, meta-analysts do not give close attention to the possibility that these interrelated differences among studies are related in complex ways to study effect sizes and, consequently, run considerable risk of reporting results that are misleading or flatly wrong. To remedy this situation, improvements are needed in both the method and practice of meta-analysis so that greater attention can be given to effect size variation, the generalizability of study results, and the systematic multivariate relationships between study characteristics and the effect sizes reported in those studies.

The role of method in treatment effectiveness research: evidence from meta-analysis.

A synthesis of 319 meta-analyses of psychological, behavioral, and educational treatment research was conducted to assess the influence of study method on observed effect sizes relative to that of substantive features of the interventions. An index was used to estimate the proportion of effect size variance associated with various study features. Study methods accounted for nearly as much variability in study outcomes as characteristics of the interventions. Type of research design and operationalization of the dependent variable were the method features associated with the largest proportion of variance. The variance as a result of sampling error was about as large as that associated with the features of the interventions studied. These results underscore the difficulty of detecting treatment outcomes, the importance of cautiously interpreting findings from a single study, and the importance of meta-analysis in summarizing results across studies.

Evaluation methods for social intervention.

Experimental design is the method of choice for establishing whether social interventions have the intended effects on the populations they are presumed to benefit. Experience with field experiments, however, has revealed significant limitations relating chiefly to (a) practical problems implementing random assignment, (b) important uncontrolled sources of variability occurring after assignment, and (c) a low yield of information for explaining why certain effects were or were not found. In response, it is increasingly common for outcome evaluation to draw on some form of program theory and extend data collection to include descriptive information about program implementation, client characteristics, and patterns of change. These supplements often cannot be readily incorporated into standard experimental design, especially statistical analysis. An important advance in outcome evaluation is the recent development of statistical models that are able to represent individual-level change, correlates of change, and program effects in an integrated and informative manner.

Predicting tobacco use to age 18: a synthesis of longitudinal research.

AIMS: To synthesize the available evidence on predictors of adolescent tobacco use. DESIGN: Meta-analysis was conducted on the empirical findings of published and unpublished studies of the natural development of tobacco use that used prospective multi-wave panel designs. PARTICIPANTS: The research literature that was analyzed included 106 reports on 64 studies representing data from a total of 145,750 study subjects; 1261 prospective and cross-sectional effect sizes were computed from these studies and used in the meta-analysis. MEASUREMENTS: Product-moment correlations were analyzed examining the strength of the relationships between predictor variables and current and later tobacco use. In addition, findings reported as 2 x 2 contingency tables were analyzed to examine conditional relations and estimate the positive predicted values (PPV) and sensitivity indices for the predictive relationships. FINDINGS: The mean correlations for 17 different categories of predictors and current or later tobacco use ranged from -0.08 for race to 0.52 for prior tobacco use and were significant and positive except for race. Analysis of the conditional relationships showed that PPV for tobacco use ranged from a mean of 0.18 for predictors related to personal skills and knowledge (i.e. 82% of those 'at risk' on this construct did not use tobacco) to 0.70 for use of tobacco or other substances by parents. CONCLUSIONS: Current use of tobacco and other substances by youths, and use among their peers, showed stronger relationships with later tobacco use than other examined predictors. Combined with other predictive risk factors, these relationships are sufficiently strong to be useful in identifying for intervention those children most likely to become habitual tobacco users.

Is there a causal relationship between alcohol use and violence? A synthesis of evidence.

This chapter reviews the evidence bearing on the question of whether those individuals who consume alcohol have an increased probability of subsequent violent behavior. Four bodies of relevant research are examined: experimental studies with animals, experimental studies with humans, individual-level correlational studies, and macro-level correlational studies. All these research approaches provide some evidence of an association between alcohol consumption and violent behavior, but no firm conclusion can be drawn about whether alcohol plays a causal role in such behavior. Various limitations, deficiencies, and ambiguities of available research that contribute to this state of affairs are discussed.

Key issues in intervention research: a program evaluation perspective.

Over the last two decades, theory and practice in the field of program evaluation have generated a rich array of concepts and methods for research on the effectiveness of social programs. This paper attempts to summarize the lessons from program evaluation research that might usefully inform intervention research in occupational health and safety.

The efficacy of psychological, educational, and behavioral treatment. Confirmation from meta-analysis.

Conventional reviews of research on the efficacy of psychological, educational, and behavioral treatments often find considerable variation in outcome among studies and, as a consequence, fail to reach firm conclusions about the overall effectiveness of the interventions in question. In contrast meta-analytic reviews show a strong, dramatic pattern of positive overall effects that cannot readily be explained as artifacts of meta-analytic technique or generalized placebo effects. Moreover, the effects are not so small that they can be dismissed as lacking practical or clinical significance. Although meta-analysis has limitations, there are good reasons to believe that its results are more credible than those of conventional reviews and to conclude that well-developed psychological, educational, and behavioral treatment is generally efficacious.

A practitioner's guide to meta-analysis.

Describes the application to community issues of the meta-analytic research strategies increasingly used in many field of psychology. First, we highlight the potential value of meta-analysis to community research. Second, we describe six major steps involved in conducting an effective meta-analysis. These steps include formulating the initial research question(s), locating relevant studies, abstracting critical information from each study, and presenting, analyzing, and interpreting the resultant data. In this guide, the major aspects of meta-analysis are discussed with particular emphasis on the procedures that are most critical to the validity of its conclusions. Greater familiarity with the techniques, issues, and potential of meta-analysis may stimulate investigators to make more effective use of this powerful approach to integrating research in community psychology.

Public attitudes toward science and technology: what have the surveys told us?

Surveys of public attitudes toward science and technology over the last two decades show a very high level of favorable response. Public confidence in science sagged in the seventies and, though science suffered considerably less than most other major social institutions, a larger tiny minority now view it as harmful than in the fifties. The most striking aspect of public attitudes toward science, and scientists, however, is that they appear to be based on nebulous and distorted conceptions which are dominated by themes of applied technology.