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Statistical testing of a new testate amoeba-based transfer function for water-table depth reconstruction on ombrotrophic peatlands in north-eastern Canada and Maine, United States

Statistical testing of a new testate amoeba-based transfer function for water-table depth reconstruction on ombrotrophic peatlands in north-eastern Canada and Maine, United States
Statistical testing of a new testate amoeba-based transfer function for water-table depth reconstruction on ombrotrophic peatlands in north-eastern Canada and Maine, United States
Proxy reconstructions of climatic parameters developed using transfer functions are central to the testing of many palaeoclimatic hypotheses on Holocene timescales. However, recent work shows that the mathematical models underpinning many existing transfer functions are susceptible to spatial autocorrelation, clustered training set design and the uneven sampling of environmental gradients. This may result in over-optimistic performance statistics or, in extreme cases, a lack of predictive power. A new testate amoeba-based transfer function is presented that fully incorporates the new recommended statistical tests to address these issues. Leave-one-out cross-validation, the most commonly applied method in recent studies to assess model performance, produced over-optimistic performance statistics for all models tested. However, the preferred model, developed using weighted averaging with tolerance downweighting, retained a predictive capacity equivalent to other published models even when less optimistic performance statistics were chosen. Application of the new statistical tests in the development of transfer functions provides a more thorough assessment of performance and greater confidence in reconstructions based on them. Only when the wider research community have sufficient confidence in transfer function-based proxy reconstructions will they be commonly used in data comparison and palaeoclimate modelling studies of broader scientific relevance.
cross-validation, north america, peat, testate amoebae, transfer function
0267-8179
27-39
Amesbury, Matthew
84a60fe0-4916-45c4-8515-20aa539ac870
Mallon, Gunnar
579c5070-3c15-4405-abe2-ea0b2203a5fc
Charman, Dan
41be0090-9d2e-487c-b9d4-151b93a80f3a
Hughes, Paul
14f83168-b203-4a91-a850-8c48535dc31b
Booth, Robert
36b92a84-2ccc-424e-8418-040846053639
Daley, Tim
87b6f2fa-550d-4e46-a04c-40c47d89c0f5
Garneau, Michelle
3c5bd5e9-a326-476a-a5aa-e80c8db8ae34
Amesbury, Matthew
84a60fe0-4916-45c4-8515-20aa539ac870
Mallon, Gunnar
579c5070-3c15-4405-abe2-ea0b2203a5fc
Charman, Dan
41be0090-9d2e-487c-b9d4-151b93a80f3a
Hughes, Paul
14f83168-b203-4a91-a850-8c48535dc31b
Booth, Robert
36b92a84-2ccc-424e-8418-040846053639
Daley, Tim
87b6f2fa-550d-4e46-a04c-40c47d89c0f5
Garneau, Michelle
3c5bd5e9-a326-476a-a5aa-e80c8db8ae34

Amesbury, Matthew, Mallon, Gunnar, Charman, Dan, Hughes, Paul, Booth, Robert, Daley, Tim and Garneau, Michelle (2013) Statistical testing of a new testate amoeba-based transfer function for water-table depth reconstruction on ombrotrophic peatlands in north-eastern Canada and Maine, United States. Journal of Quaternary Science, 28 (1), 27-39. (doi:10.1002/jqs.2584).

Record type: Article

Abstract

Proxy reconstructions of climatic parameters developed using transfer functions are central to the testing of many palaeoclimatic hypotheses on Holocene timescales. However, recent work shows that the mathematical models underpinning many existing transfer functions are susceptible to spatial autocorrelation, clustered training set design and the uneven sampling of environmental gradients. This may result in over-optimistic performance statistics or, in extreme cases, a lack of predictive power. A new testate amoeba-based transfer function is presented that fully incorporates the new recommended statistical tests to address these issues. Leave-one-out cross-validation, the most commonly applied method in recent studies to assess model performance, produced over-optimistic performance statistics for all models tested. However, the preferred model, developed using weighted averaging with tolerance downweighting, retained a predictive capacity equivalent to other published models even when less optimistic performance statistics were chosen. Application of the new statistical tests in the development of transfer functions provides a more thorough assessment of performance and greater confidence in reconstructions based on them. Only when the wider research community have sufficient confidence in transfer function-based proxy reconstructions will they be commonly used in data comparison and palaeoclimate modelling studies of broader scientific relevance.

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e-pub ahead of print date: 30 October 2012
Published date: January 2013
Keywords: cross-validation, north america, peat, testate amoebae, transfer function
Organisations: Palaeoenvironment Laboratory (PLUS)

Identifiers

Local EPrints ID: 363625
URI: https://eprints.soton.ac.uk/id/eprint/363625
ISSN: 0267-8179
PURE UUID: fa144c12-bc91-4777-a7f3-993a0cd4d1db

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Date deposited: 27 Mar 2014 16:45
Last modified: 19 Jul 2019 21:15

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Contributors

Author: Matthew Amesbury
Author: Gunnar Mallon
Author: Dan Charman
Author: Paul Hughes
Author: Robert Booth
Author: Tim Daley
Author: Michelle Garneau

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