Ninth Edition CoverGraziano & Raulin
Research Methods (9th edition)

Examples of Studies 
Using Meta-Analysis

Example #1

Segool, N. S., & Carlsen, J. S. (2008). Efficacy of cognitive-behavioral and pharmacological treatments for children with social anxiety. Depression and Anxiety, 25, 620-631.


Childhood social anxiety is a common disorder with significant academic and social impairment. The researchers evaluated the effectiveness of cognitive-behavior therapy and pharmacological treatment (selective serotonin reuptake inhibitor [SSRI]). A literature search found 14 studies that met all of the inclusion criteria for the meta-analysis. These studies compared pre- and post-treatment measures of social anxiety core symptoms, peripheral general anxiousness, and measures of social competency and social impairment.  The meta-analysis found that both cognitive behavior therapy and pharmacological treatment successfully reduced the core symptoms of social anxiety and social impairment and reduced the peripheral symptoms of general anxiousness. Both treatments also resulted in moderate improvements in social competence. Implications of these findings for treatment were discussed by the authors.

Example # 2 

Conner, K. R., Pinquart, M., & Holbrook, A. (2008). Meta-analysis of depression and substance use and impairment among cocaine users. Drug and Alcohol Dependence, 98, 13-23.


It has long been hypothesized that drug and alcohol use is associated with depression and serious impairment. Some treatments attempt to deal with the depression as a route to reducing the substance use. This study evaluated the hypotheses, among cocaine users, of an association of depression with (1) cocaine use and impairment , (2) alcohol use and impairment, and (3) general drug use and impairment. The hypothesis that women compared with men would show a stronger correlation between depression, substance use and impairment was also tested.

Sixty studies were identified in the literature search that met the inclusion criteria for the meta-analysis. As hypothesized, depression was found to be associated with cocaine, alcohol, and general drug use and impairment. The hypothesized relationship of gender to depression, drug and alcohol use, and impairment, however, was not supported.

Example #3

Anderson, C. A., & Bushman, B. B. (2001). Effects of violent video games on aggressive behavior, aggressive cognition, aggressive affect, physiological arousal, and pro-social behavior: A meta-analytic review of the scientific literature. Psychological Science, 12, 353-359.


In their literature review, the authors note that half a century of sophisticated research on the effects of exposure to violent movies and television has amply documented that: even brief exposure to media violence brings about significant increases in aggressive behavior; children's repeated exposure to violent programming leads to their increased aggression as adults and; such media violence is a significant risk factor in the real-world violence of youth. We know that television and movies have such effects but, the researchers asked, does playing violent video games have similar effects on increasing aggressive behavior? The research on this question is not as extensive, because this is a more recent phenomenon. Two main questions were examined in this meta-analysis: (1) "Is exposure to violent media games associated with increased aggression?"; (2) "How can such exposure increase aggression?"

An electronic search was conducted of PsycINFO for all years through 2000, using the search terms: (video or computer or arcade) and (game) and (attack or fight or aggress or violence or hostile or anger or pro-social or help). The latter two search terms were included because earlier research suggested that pro-social behavior and violent media are negatively related. The search identified 35 research articles that included 54 independent samples and a total of 4,262 participants. 

The meta-analysis of the results of the 35 articles examined whether there is a reliable association between exposure to violent video games and each of five dependent measures: aggressive behavior; aggressive cognition; aggressive affect; pro-social behavior; physiological arousal.

The results of the meta-analysis showed there was a significant positive relationship between exposure to violent video games and aggressive behavior, aggressive cognition, aggressive affect, and physiological arousal. There was a significant negative relationship with pro-social behavior. 

The researchers concluded that exposure to violence through violent video games poses a public health threat. 

Example #4

Schneider, L. S., Dagerman, K., & Insel, P. (2005). Risk of death with atypical antipsychotic drug treatment for dementia: meta-analysis of randomized placebo-controlled trials. JAMA: Journal of the American Medical Association, 294, 1934-1943.


Elderly persons with Alzheimer’s disease are frequently treated with antipsychotic medications for delusions, aggression, and agitation. While the treatments appear to help control those serious problems, there is growing concern that drugs may increase risks for cerebrovascular problems, cognitive deterioration, and even death. 

The main question of this study is whether antipsychotic drugs increase the risk of death for people with dementia.

The meta analysis selected and evaluated published and unpublished studies that, when pooled, totaled 3353 patients randomly assigned to drug treatment and 1757 randomly assigned to placebo.

A slightly higher proportion of deaths (3.5%) occurred in the drug-treated patients than in the placebo controls (2.3%). No other risk differences between the groups were found. The authors concluded that antipsychotic drugs administered to elderly persons may be associated with slightly higher risk of death compared with placebo.

Example #5

Den Boer, P. C., Wiersma, D., & Van Den Bosch, R. J. (2004). Why is self-help neglected in the treatment of emotional disorders? Psychological Medicine, 34, 959-971.


Despite high rates of emotional disorders in the population, mental health care is available to only a very few. Some research suggests that self-help strategies such as and self-help groups can be effective for persons with less serious emotional disorders. But the research evidence is not clear as to whether the relatively inexpensive and more readily provided self-help strategies can be helpful for persons with clinically significant emotional disorders.

Treatment literature on anxiety and/or depressive disorder was searched for 1970-2000. Nine characteristics were used to assess methodological quality, and only 14 studies (14 patients) survived the inclusion criteria. The studies included in the meta-analysis were randomized controlled trials.

 Results show a markedly robust effect of bibliotherapy--essentially self-help versions of cognitive behavioral therapy--versus waiting list or no treatment controls, with a mean effect size of .84.  Results also showed the self-help to be as effective as short-duration professional treatment.  

The major weakness of this study is the small number of primary studies that were found and analyzed. However the findings of such strong effects demand serious consideration of these self-help therapies for fairly serious disorders, as a way of making reasonable help more available. At least the results demand more research investigation. 

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