Primary, Secondary, and Meta-Analysis of Research

Glass, Gene V.

doi:10.3102/0013189x005010003

Cited by 4,043 publications

(1,930 citation statements)

References 7 publications

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“…If Option B is used, only the sample sizes and variances for the groups included in the contrast are included in the calculation of S 2 pooled . An argument against Option B, presented in Hedges (1981) but attributed to Glass (1976), concerns the possibility that two estimated contrasts that are identical in size will have unequal values for δ if Option B is used. If the evidence suggests that all J variances estimate the same population variance (i.e., the variances meet the equality of variance assumption) then Option C is the best option.…”

Section: Between-subjects Designsmentioning

confidence: 99%

Measures of Effect Size for Comparative Studies: Applications, Interpretations, and Limitations

Olejnik¹,

Algina

2000

Contemporary Educational Psychology

578

370

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Although dissatisfaction with the limitations associated with tests for statistical significance has been growing for several decades, applied researchers have continued to rely almost exclusively on these indicators of effect when reporting their findings. To encourage an increased use of alternative measures of effect, the present paper discusses several measures of effect size that might be used in group comparison studies involving univariate and/or multivariate models. For the methods discussed, formulas are presented and data from an experimental study are used to demonstrate the application and interpretation of these indices. The paper concludes with some cautionary notes on the limitations associated with these measures of effect size.

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Section: Between-subjects Designsmentioning

confidence: 99%

Measures of Effect Size for Comparative Studies: Applications, Interpretations, and Limitations

Olejnik¹,

Algina

2000

Contemporary Educational Psychology

578

370

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“…However, results from a single experiment will not provide a definitive understanding of the effect of SR treatment because the conditions under which observations are made in a single experiment are inevitably narrow (Sauvant et al, 2008). A meta-analysis approach (Glass, 1976), summarising the results across published studies in a particular area and in combination with new statistical techniques, allows increased precision of analysis of effects across multiple experiments (St-Pierre, 2001;Sauvant et al, 2008;Lean et al, 2009). In a historical review of SR experiments, Journet and Demarquilly (1979) reported that an SR increase of one cow/ha resulted in a mean reduction in milk production per cow of 10%, but an increase in production per ha of over 20%.…”

Section: Introductionmentioning

confidence: 99%

Meta-analysis of the impact of stocking rate on the productivity of pasture-based milk production systems

McCarthy

Delaby

Pierce

et al. 2011

Animal

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The objective of this study is to quantify the milk production response per cow and per hectare (ha) for an incremental stocking rate (SR) change, based on a meta-analysis of published research papers. Suitable experiments for inclusion in the database required a comparison of at least two SRs under the same experimental conditions in addition to details on experimental length and milk production results per cow and per ha. Each additional increased SR treatment was also described in terms of the relative milk production change per cow and per ha compared to the lower base SR (b_SR). A database containing 109 experiments of various lengths with 131 comparisons of SR was sub-divided into Type I experiments (common experimental lengths) and Type II experiments (variable experimental lengths). Actual and proportional changes in milk production according to SR change were analysed using linear mixed model procedures with study included as a random effect in the model. Low residual standard errors indicated a good precision of the predictive equations with the exception of proportional change in milk production per cow. For all milk yield variables analysed, the results illustrate that while production per cow is reduced, a strong positive relationship exists between SR and milk production per ha. An SR increase of one cow/ha resulted in a decrease in daily milk yield per cow of 7.4% and 8.7% for Type I and Type II data, respectively, whereas milk yield per ha increased by 20.1% and 19.6%, respectively. Within the Type II data set, a one cow/ha increase in SR also resulted in a 15.1% reduction in lactation length (equivalent to 42 days). The low predictability of proportional change in milk production per cow according to the classical SR definition of cows per ha over a defined period suggests that SR may be more appropriately defined in terms of the change in available feed offered per animal within each treatment.

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“…Currently, the use of quantitative methods to summarize results from various empirical studies that test the same hypothesis is widespread in education, psychology, medicine, and social science research. Metaanalysis is a statistical method used to combine evidence from different primary research studies that test comparable hypotheses for the purposes of summarizing evidence and drawing general conclusions (Cooper et al, 2009;Glass, 1976;Hedges & Olkin, 1985;Lipsey & Wilson, 2001). …”

mentioning

confidence: 99%

Fixed effects and variance components estimation in three-level meta-analysis

2011

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Standard-Nutzungsbedingungen:Die Dokumente auf EconStor dürfen zu eigenen wissenschaftlichen Zwecken und zum Privatgebrauch gespeichert und kopiert werden.Sie dürfen die Dokumente nicht für öffentliche oder kommerzielle Zwecke vervielfältigen, öffentlich ausstellen, öffentlich zugänglich machen, vertreiben oder anderweitig nutzen.Sofern die Verfasser die Dokumente unter Open-Content-Lizenzen (insbesondere CC-Lizenzen) zur Verfügung gestellt haben sollten, gelten abweichend von diesen Nutzungsbedingungen die in der dort genannten Lizenz gewährten Nutzungsrechte. www.econstor.eu The Institute for the Study of Labor (IZA) in Bonn is a local and virtual international research center and a place of communication between science, politics and business. IZA is an independent nonprofit organization supported by Deutsche Post Foundation. The center is associated with the University of Bonn and offers a stimulating research environment through its international network, workshops and conferences, data service, project support, research visits and doctoral program. IZA engages in (i) original and internationally competitive research in all fields of labor economics, (ii) development of policy concepts, and (iii) dissemination of research results and concepts to the interested public. Terms of use: Documents in D I S C U S S I O N P A P E R S E R I E SIZA Discussion Papers often represent preliminary work and are circulated to encourage discussion. Citation of such a paper should account for its provisional character. A revised version may be available directly from the author.IZA Discussion Paper No. 5678 April 2011 ABSTRACT Fixed Effects and Variance Components Estimation inThree-Level Meta-Analysis * Meta-analytic methods have been widely applied to education, medicine, and the social sciences. Much of meta-analytic data are hierarchically structured since effect size estimates are nested within studies, and in turn studies can be nested within level-3 units such as laboratories or investigators, and so forth. Thus, multilevel models are a natural framework for analyzing meta-analytic data. This paper discusses the application of a Fisher scoring method in two-and three-level meta-analysis that takes into account random variation at the second and at the third levels. The usefulness of the model is demonstrated using data that provide information about school calendar types. SAS proc mixed and HLM can be used to compute the estimates of fixed effects and variance components.JEL Classification: C00

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Primary, Secondary, and Meta-Analysis of Research

Cited by 4,043 publications

References 7 publications

Measures of Effect Size for Comparative Studies: Applications, Interpretations, and Limitations

Measures of Effect Size for Comparative Studies: Applications, Interpretations, and Limitations

Meta-analysis of the impact of stocking rate on the productivity of pasture-based milk production systems

Fixed effects and variance components estimation in three-level meta-analysis

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