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Related Concept Videos

Variance01:15

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The deviations show how spread out the data are about the mean. A positive deviation occurs when the data value exceeds the mean, whereas a negative deviation occurs when the data value is less than the mean. If the deviations are added, the sum is always zero. So one cannot simply add the deviations to get the data spread. By squaring the deviations, the numbers are made positive; thus, their sum will also be positive.
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Evolutionary psychology explores the origins of human behavior and mental processes by framing them within the context of natural selection, a theory famously propounded by Charles Darwin. This field asserts that many behaviors common across human societies — ranging from instinctive fear reactions to complex social interactions — arose as evolutionary adaptations. These adaptations enhanced the survival and reproductive success of our ancestors, thereby becoming embedded in the...
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All organisms have a position within an ecosystem. The complete set of living and nonliving factors—including food resources, climate, and terrain—that define the position of a given organism are collectively referred to as the organism’s ecological niche.
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Related Experiment Video

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Following the Dynamics of Structural Variants in Experimentally Evolved Populations
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How much variance can be explained by ecologists and evolutionary biologists?

Anders Møller1, Michael D Jennions2,3

  • 1Laboratoire d'Ecologie Evolutive Parasitaire, CNRS UMR 7103, Université Pierre et Marie Curie, 7 quai St. Bernard, Case 237, 75252, Paris Cedex 05, France. amoller@snv.jussieu.fr.

Oecologia
|May 27, 2017
PubMed
Summary
This summary is machine-generated.

Ecological and evolutionary studies explain only 2.5-5.4% of variance. This meta-analysis highlights the need for larger sample sizes to detect meaningful effects in these fields.

Keywords:
EcologyEffect sizeEvolutionMeta-analysisSample size

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Area of Science:

  • Ecology
  • Evolutionary Biology
  • Meta-analysis

Background:

  • Evaluating the strength of research findings is crucial in ecology and evolutionary studies.
  • Theoretical expectations of explaining 100% of variance are often unmet due to biological noise.

Purpose of the Study:

  • To quantify the average variance explained by main factors in ecological and evolutionary research.
  • To assess implications for study design and interpretation of effect sizes.

Main Methods:

  • A meta-analysis of 43 published meta-analyses in ecology and evolution was conducted.
  • Data included 93 estimates using Pearson's r and 136 estimates using Hedges' d or g.

Main Results:

  • The mean variance (r²) explained was 2.51-5.42%, with 95% confidence intervals between 1.99-7.05%.
  • Variance explained differed by field: physiological ecology > ecology > evolutionary studies.
  • A positive relationship was found between fail-safe numbers and effect sizes (r²).

Conclusions:

  • Key factors in ecological and evolutionary studies explain a small proportion of the variance in traits of interest.
  • Average effect sizes (Pearson r=0.180-0.193, Hedges' d=0.631-0.721) necessitate larger sample sizes than typically used.
  • Findings impact the interpretation of scientific studies and planning of future research.