Practical Matters: Which Model Should I Use?

In Sections 10.1 and 10.2, I have presented the random-effects model for estimating mean effect sizes, which can be contrasted with the fixed-effects model I described in Chapter 8. I have also described (Section 10.3) mixed- effects models, in which (fixed) moderators are evaluated in the context of conditional random heterogeneity; this section can

The Problem of Publication Bias of Meta-Analysis

Publication bias refers to the possibility that studies finding null (absence of statistically significant effect) or negative (statistically significant effect in opposite direction expected) results are less likely to be published than studies finding positive effects (statistically significant effects in expected direction).1 This bias is likely due both to researchers being less motivated to

Managing Publication Bias of Meta-Analysis

In this section, I describe six approaches to managing publication bias within meta-analysis. I also illustrate some of these approaches through the example meta-analysis I have used throughout this book: a review of 22 studies report­ing associations between relational aggression and peer rejection among chil­dren and adolescents. In Chapter 8, I presented results of

Practical Matters: What Impact Do Sampling Biases Have on Meta-Analytic Conclusions?

The short answer to the question, “What impact do sampling biases have on the conclusions of a meta-analysis?” is “I don’t know.” As a meta-analyst you do not know, your readers do not know, and it is not possible to know unless you could obtain every study that has ever been conducted on the

Meta-Analysis to Obtain Sufficient Statistics

1. Sufficient Statistics for Multivariate Analyses As you may recall (fondly or not) from your multivariate statistics courses, nearly all multivariate analyses do not require the raw data. Instead, you can perform these analyses using sufficient statistics—summary information from your data that can be inserted into matrix equations to provide esti­mates of multivariate parameters.

Two Approaches to Multivariate Meta-Analysis

Given the challenges I described in the previous section, multivariate meta­analysis is considerably more complex than simply synthesizing several corre­lations to serve as input for a multivariate analysis. The development of models that can manage these challenges is an active area of research, and the field has currently not resolved which approach is best.

Practical Matters: The Interplay between Meta-Analytic Models and Theory

As with any data-analytic approach, meta-analytic techniques are most valu­able when applied in the service of theories relevant to the content of your review. I place this discussion on the interplay between meta-analysis and theory in this chapter on multivariate meta-analysis because many of our theories are multivariate and therefore benefit from multivariate analyses.

Dimensions of Literature Reviews, Revisited in writing Meta-Analytic Results

Before I turn to specific recommendations for writing the results of your meta-analysis, it is important for you to recognize that there is no single “right” way to write these results. As I described in Chapter 1 (see also Coo­per, 1988), literature reviews vary along several dimensions. Before you begin to write the results

What to Report and Where to Report It

In this section, I discuss the basic structural sections of a manuscript and special considerations in reporting meta-analytic results within these sec­tions. Two caveats are in order here. First, I expect that you are aware of the ways that manuscripts (whether primary studies or meta-analyses) are struc­tured within your field, in terms of what

Using Tables and Figures in Reporting Meta-Analyses

Tables and figures, if used effectively, can provide a large amount of data in an informative way, as well as reduce the burden of describing all of this information within the text (though you should not omit key findings from the text just because they are also displayed in tables or figures). In this

Practical Matters: Avoiding Common Problems in Reporting Results of Meta-Analyses

In this section, I identify 10 problems that I perceive to be common in report­ing results of meta-analytic reviews. More importantly, I offer concrete sug­gestions for how you can avoid each. Although following these suggestions will not guarantee that your meta-analytic report will be successful (whether defined by publication in a top-outlet, high-impact, or

Applications of Statistics in Business and Economics

In today’s global business and economic environment, anyone can access vast amounts of statistical information. The most successful managers and decision makers understand the information and know how to use it effectively. In this section, we provide examples that illustrate some of the uses of statistics in business and economics. 1. Accounting Public accounting

Types of Data

Data are the facts and figures collected, analyzed, and summarized for presentation and interpretation. All the data collected in a particular study are referred to as the data set for the study. Table 1.1 shows a data set containing information for 60 nations that participate in the World Trade Organization. The World Trade Organization

Data Sources

Data can be obtained from existing sources, by conducting an observational study, or by conducting an experiment. 1. Existing Sources In some cases, data needed for a particular application already exist. Companies maintain a va­riety of databases about their employees, customers, and business operations. Data on employee salaries, ages, and years of experience can

Descriptive Statistics

Most of the statistical information in the media, company reports, and other publications consists of data that are summarized and presented in a form that is easy for the reader to understand. Such summaries of data, which may be tabular, graphical, or numerical, are referred to as descriptive statistics. Refer to the data set

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Statistical Inference

Many situations require information about a large group of elements (individuals, compa­nies, voters, households, products, customers, and so on). But, because of time, cost, and other considerations, data can be collected from only a small portion of the group. The larger group of elements in a particular study is called the population, and the

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Data Analytics

Because of the dramatic increase in available data, more cost-effective data storage, faster computer processing, and recognition by managers that data can be extremely valuable for understanding customers and business operations, there has been a dramatic increase in data-driven decision making. The broad range of techniques that may be used to support data-driven decisions

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Big Data and Data Mining

With the aid of magnetic card readers, bar code scanners, and point-of-sale terminals, most organizations obtain large amounts of data on a daily basis. And, even for a small local restaurant that uses touch screen monitors to enter orders and handle billing, the amount of data collected can be substantial. For large retail companies,

Computers and Statistical Analysis

Statisticians use computer software to perform statistical computations and analyses. For example, computing the average time until recharge for the 200 batteries in the Rogers Industries example (see Table 1.5) would be quite tedious without a computer. End-of-chapter appendixes cover the step-by-step procedures for using Microsoft Excel and the statistical package JMP to implement

Ethical Guidelines for Statistical Practice

Ethical behavior is something we should strive for in all that we do. Ethical issues arise in statistics because of the important role statistics plays in the collection, analysis, presenta­tion, and interpretation of data. In a statistical study, unethical behavior can take a variety of forms including improper sampling, inappropriate analysis of the data,