Using causal diagrams and superpopulation models to correct geographic biases in biodiversity monitoring data

Abstract Biodiversity monitoring schemes periodically measure species' abundances and distributions at a sample of sites to understand how they have changed over time. Often, the aim is to infer change in an average sense across some wider landscape. Inference to the wider landscape is simple i...

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Main Authors: Robin J. Boyd, Marc Botham, Emily Dennis, Richard Fox, Collin Harrower, Ian Middlebrook, David B. Roy, Oliver L. Pescott
Format: Article
Language:English
Published: Wiley 2025-02-01
Series:Methods in Ecology and Evolution
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Online Access:https://doi.org/10.1111/2041-210X.14492
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author Robin J. Boyd
Marc Botham
Emily Dennis
Richard Fox
Collin Harrower
Ian Middlebrook
David B. Roy
Oliver L. Pescott
author_facet Robin J. Boyd
Marc Botham
Emily Dennis
Richard Fox
Collin Harrower
Ian Middlebrook
David B. Roy
Oliver L. Pescott
author_sort Robin J. Boyd
collection DOAJ
description Abstract Biodiversity monitoring schemes periodically measure species' abundances and distributions at a sample of sites to understand how they have changed over time. Often, the aim is to infer change in an average sense across some wider landscape. Inference to the wider landscape is simple if the species' abundances and distributions are similar at sampled to non‐sampled locations. Otherwise, the data are geographically biased, and some form of correction is desirable. We combine causal diagrams with ‘superpopulation models’ to correct time‐varying geographic biases in biodiversity monitoring data. For a given time‐period, expert‐derived causal diagrams are used to deduce the set of variables that explain the geographic bias, and superpopulation models adjust for these variables to produce a corrected estimate of a landscape‐wide mean of for example abundance or occupancy. Estimating a time trend in the variable of interest is achieved by fitting models for multiple time‐periods and, if the drivers of bias are suspected to change over time, by constructing per period causal diagrams. We test the approach using simulated data then apply it to real data from the UK Butterfly Monitoring Scheme (UKBMS). If the variables that explain the geographic bias are known and measured without error, our method is unbiased. Introducing measurement error reduces the method's efficacy, but it is still an improvement on using the sample mean. When applied to data from the UKBMS, the approach gives different results to the scheme's current method, which assumes no geographic bias. Where the goal is to estimate change in some variable of interest at the landscape level (e.g. biodiversity indicators), models that do not adjust for geographic bias implicitly assume it does not exist. Our approach makes the weaker assumption that there is no geographic bias conditional on the adjustment variables, so it should yield more accurate estimates of time trends in many circumstances. The method does require assumptions about the drivers of bias, but these are codified explicitly in the causal diagrams. Operationalising our approach should be less costly than full probability sampling, which would be needed to satisfy the assumptions of conventional approaches.
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spelling doaj-art-b3ad9db0a3d04e1ca465cadb28419bfa2025-02-05T05:43:20ZengWileyMethods in Ecology and Evolution2041-210X2025-02-0116233234410.1111/2041-210X.14492Using causal diagrams and superpopulation models to correct geographic biases in biodiversity monitoring dataRobin J. Boyd0Marc Botham1Emily Dennis2Richard Fox3Collin Harrower4Ian Middlebrook5David B. Roy6Oliver L. Pescott7UK Centre for Ecology and Hydrology Crowmarsh Gifford UKUK Centre for Ecology and Hydrology Crowmarsh Gifford UKButterfly Conservation Wareham UKButterfly Conservation Wareham UKUK Centre for Ecology and Hydrology Crowmarsh Gifford UKButterfly Conservation Wareham UKUK Centre for Ecology and Hydrology Crowmarsh Gifford UKUK Centre for Ecology and Hydrology Crowmarsh Gifford UKAbstract Biodiversity monitoring schemes periodically measure species' abundances and distributions at a sample of sites to understand how they have changed over time. Often, the aim is to infer change in an average sense across some wider landscape. Inference to the wider landscape is simple if the species' abundances and distributions are similar at sampled to non‐sampled locations. Otherwise, the data are geographically biased, and some form of correction is desirable. We combine causal diagrams with ‘superpopulation models’ to correct time‐varying geographic biases in biodiversity monitoring data. For a given time‐period, expert‐derived causal diagrams are used to deduce the set of variables that explain the geographic bias, and superpopulation models adjust for these variables to produce a corrected estimate of a landscape‐wide mean of for example abundance or occupancy. Estimating a time trend in the variable of interest is achieved by fitting models for multiple time‐periods and, if the drivers of bias are suspected to change over time, by constructing per period causal diagrams. We test the approach using simulated data then apply it to real data from the UK Butterfly Monitoring Scheme (UKBMS). If the variables that explain the geographic bias are known and measured without error, our method is unbiased. Introducing measurement error reduces the method's efficacy, but it is still an improvement on using the sample mean. When applied to data from the UKBMS, the approach gives different results to the scheme's current method, which assumes no geographic bias. Where the goal is to estimate change in some variable of interest at the landscape level (e.g. biodiversity indicators), models that do not adjust for geographic bias implicitly assume it does not exist. Our approach makes the weaker assumption that there is no geographic bias conditional on the adjustment variables, so it should yield more accurate estimates of time trends in many circumstances. The method does require assumptions about the drivers of bias, but these are codified explicitly in the causal diagrams. Operationalising our approach should be less costly than full probability sampling, which would be needed to satisfy the assumptions of conventional approaches.https://doi.org/10.1111/2041-210X.14492directed acyclic graphexpert consultationimputationsampling biasspecies abundancetime trend
spellingShingle Robin J. Boyd
Marc Botham
Emily Dennis
Richard Fox
Collin Harrower
Ian Middlebrook
David B. Roy
Oliver L. Pescott
Using causal diagrams and superpopulation models to correct geographic biases in biodiversity monitoring data
Methods in Ecology and Evolution
directed acyclic graph
expert consultation
imputation
sampling bias
species abundance
time trend
title Using causal diagrams and superpopulation models to correct geographic biases in biodiversity monitoring data
title_full Using causal diagrams and superpopulation models to correct geographic biases in biodiversity monitoring data
title_fullStr Using causal diagrams and superpopulation models to correct geographic biases in biodiversity monitoring data
title_full_unstemmed Using causal diagrams and superpopulation models to correct geographic biases in biodiversity monitoring data
title_short Using causal diagrams and superpopulation models to correct geographic biases in biodiversity monitoring data
title_sort using causal diagrams and superpopulation models to correct geographic biases in biodiversity monitoring data
topic directed acyclic graph
expert consultation
imputation
sampling bias
species abundance
time trend
url https://doi.org/10.1111/2041-210X.14492
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