Ch. 14 Research Synthesis (Meta-Analysis)

The inclusion criteria in a meta-analysis are very much like

Delimitations

The fact that a meta-analysis quantifies findings from many studies is a frequently mentioned advantage. Another strong advantage of the meta-analysis over the normal review paper is

The description of the coding of study characteristics and the criteria for excluding studies

Discuss the ramifications of the "file-drawer" effect on meta-analyses

There may be some number of studies on any topic that have been submitted to or published in scholarly journals. This is the "file-drawer" effect. The meta-analyst should find every study possible but account for those studies that have not been reported (and may have been left in a file drawer)

In a meta-analysis, the researcher found that the mean for the experimental group in a study was 14, and the mean for the control group was 10. The standard deviation of the control group was 5. Based on these data, what is the ES?

0.80

It is common when looking at a distribution to encounter extreme or unusual scores that could have a misleading effect on the results. Theses extreme scores are termed

Outliers

A major difference in the purpose of a meta-analysis and a review of literature for a research paper is that the meta-analysis uses the literature

For empirical and theoretical conclusions

In a meta-analysis of 100 studies that compared boys' and girls' knowledge of AIDS, an average ES of 0.50 was found. This number represents

A difference of 0.50 standard deviation units

In meta-analysis, the results of various studies on a topic are quantified using a standard measure (ES) that is called

Effect Size

Explain how a single study can have more than one (1) ES. Give an example

From an intuitive perspective, the control group's variability represents the "normal" variation in an untreated population. The control group's standard deviation also has the advantage of assigning equal ESs to equal treatment means when a study contains two (2) or more experimental groups that have heterogeneous variances. Therefore, the control gorup's deviation serves as a common standard metric from which treatment differences can be compared

Explain the purpose and procedures of a meta-analysis to someone who has never heard of the research technique

Meta-analysis involves two (2) steps lacking in the typical literature review paper. First, a definitive methodology is reported concerning the decisions in literature analysis. Second, the results of various studies are quantified to a standard metric called effect size (ES). Procedures 1. Identify a problem 2. Perform a literature search by specified means 3. Review identified studies to determine inclusion or exclusion 4. Carefully read and evaluate to identify and code important study characteristics 5. Calculate effect size 6. Apply appropriate statistical techniques 7. Report all these steps and the outcomes in a review paper

In a meta-analysis, the ES for the experimental versus control groups was 0.68, which represents a percentile equivalent of 75. This means that

The average score of the experimental group was better than 75% of the control group's scores

In calculating ES for a treatment effect between a pretest and a post-test, the text recommends the use of which standard deviation?

The pretest standard deviation

The most frequent and severe criticism of meta-analysis is that

The studies represent wide differences in methodologies, designs, and measurements