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How often are invasion-induced ecological impacts missed?

journal contribution
posted on 2023-05-18, 08:05 authored by Davidson, A, Hewitt, CL
Managers and policy makers depend on empirical research to guide and support biosecurity measures that mitigate introduced species' impacts. Research contributing to this knowledge base generally uses null hypothesis significance testing to determine the significance of data patterns. However, reliance on traditional statistical significance testing methods, combined with small effect and sample size and large variability inherent to many impact studies, may obscure effects on native species, communities or ecosystems. This may result in false certainty of no impact. We investigated potential Type II error rates and effect sizes for 31 non-significant empirical evaluations of impact for introduced algal and crustacean species. We found low power consistently led to acceptance of Type II errors at rates 5.6-19 times greater than Type I errors (despite moderate to large effect sizes). Our results suggest that introduced species for which impact studies have statistically non-significant outcomes (often interpreted as "no impact") may potentially have large impacts that are missed due to small sample or effect sizes and/or high variation. This alarming willingness to "miss" impacts has severe implications for conservation efforts, including under-managing species' impacts and discounting the costs of Type II errors.

History

Publication title

Biological Invasions

Volume

16

Issue

5

Pagination

1165-1173

ISSN

1387-3547

Department/School

Institute for Marine and Antarctic Studies

Publisher

Springer Netherlands

Place of publication

Netherlands

Rights statement

Copyright Springer Science+Business Media Dordrecht 2013

Repository Status

  • Restricted

Socio-economic Objectives

Expanding knowledge in the biological sciences

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