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Natural funnel asymmetries. A simulation analysis of the three basic tools of meta analysis

Author

Listed:
  • Martin Paldam

    () (School of Economics and Management, Aarhus University, Denmark)

  • Laurent Callot

    (School of Economics and Management, Aarhus University, Denmark)

Abstract

Meta-analysis studies a set of estimates of one parameter with three basic tools: The funnel diagram is the distribution of the estimates as a function of their precision; the funnel asymmetry test, FAT; and the meta average, where PET is an estimate. The FAT-PET MRA is a meta regression analysis, on the data of the funnel, which jointly estimates the FAT and the PET. Ideal funnels are lean and symmetric. Empirical funnels are wide, and most have asymmetries biasing the plain average. Many asymmetries are due to censoring made during the research-publication process. The PET is tooled to correct the average for censoring. We show that estimation faults and misspecification may cause natural asymme¬tries, which the PET does not correct. If the MRA includes controls for omitted variables, the PET does correct for omitted variables bias. Thus, it is important to know the reason for an asymmetry.

Suggested Citation

  • Martin Paldam & Laurent Callot, 2010. "Natural funnel asymmetries. A simulation analysis of the three basic tools of meta analysis," Economics Working Papers 2010-01, Department of Economics and Business Economics, Aarhus University.
  • Handle: RePEc:aah:aarhec:2010-01
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    Cited by:

    1. Martin Paldam, 2013. "How do partly omitted control variables influence the averages used in meta-analysis in economics?," Economics Working Papers 2013-22, Department of Economics and Business Economics, Aarhus University.
    2. Martin Paldam, 2016. "Simulating an empirical paper by the rational economist," Empirical Economics, Springer, vol. 50(4), pages 1383-1407, June.
    3. Paldam, Martin, 2015. "Meta-analysis in a nutshell: Techniques and general findings," Economics - The Open-Access, Open-Assessment E-Journal, Kiel Institute for the World Economy (IfW), vol. 9, pages 1-14.

    More about this item

    Keywords

    Meta-analysis; funnel asymmetry; meta average;

    JEL classification:

    • B4 - Schools of Economic Thought and Methodology - - Economic Methodology
    • C9 - Mathematical and Quantitative Methods - - Design of Experiments

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